From: Hou Tao <[email protected]>
Since commit a78418e6a04c ("block: Always initialize bio IO priority on
submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
blkcg_set_ioprio(), so there will be no way to promote the io-priority
of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
greater than or equals to IOPRIO_CLASS_RT.
It seems possible to call blkcg_set_ioprio() first then try to
initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
for bio in which bi_ioprio is already initialized (e.g., direct-io), so
introduce a new promote-to-rt policy to promote the iopriority of bio to
IOPRIO_CLASS_RT if the ioprio is not already RT.
For none-to-rt policy, although it doesn't work now, but considering
that its purpose was also to override the io-priority to RT and allowing
for a smoother transition, just keep it and treat it as an alias of
the promote-to-rt policy.
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Hou Tao <[email protected]>
---
v4:
* rebased on 33afd4b76393
* Add Reviewed-by from Jan Kara
v3: https://lore.kernel.org/linux-block/[email protected]
* Use 'non-RT' instead of 'no-RT' in document (from Bagas)
* Remove repeated sentence in commit message
* Add Reviewed-by and Acked-by tags
v2: https://lore.kernel.org/linux-block/[email protected]
* Simplify the implementation of promote-to-rt (from Bart)
* Make none-to-rt to work again by treating it as an alias of
the promote-to-rt policy (from Bart & Jan)
* fix the style of new content in cgroup-v2.rst (from Bagas)
* set the default priority level to 4 instead of 0 for promote-to-rt
v1: https://lore.kernel.org/linux-block/[email protected]
Documentation/admin-guide/cgroup-v2.rst | 42 ++++++++++++++-----------
block/blk-ioprio.c | 23 ++++++++++++--
2 files changed, 44 insertions(+), 21 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index f67c0829350b..7544ce00e0cb 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2024,31 +2024,33 @@ that attribute:
no-change
Do not modify the I/O priority class.
- none-to-rt
- For requests that do not have an I/O priority class (NONE),
- change the I/O priority class into RT. Do not modify
- the I/O priority class of other requests.
+ promote-to-rt
+ For requests that have a non-RT I/O priority class, change it into RT.
+ Also change the priority level of these requests to 4. Do not modify
+ the I/O priority of requests that have priority class RT.
restrict-to-be
For requests that do not have an I/O priority class or that have I/O
- priority class RT, change it into BE. Do not modify the I/O priority
- class of requests that have priority class IDLE.
+ priority class RT, change it into BE. Also change the priority level
+ of these requests to 0. Do not modify the I/O priority class of
+ requests that have priority class IDLE.
idle
Change the I/O priority class of all requests into IDLE, the lowest
I/O priority class.
+ none-to-rt
+ Deprecated. Just an alias for promote-to-rt.
+
The following numerical values are associated with the I/O priority policies:
-+-------------+---+
-| no-change | 0 |
-+-------------+---+
-| none-to-rt | 1 |
-+-------------+---+
-| rt-to-be | 2 |
-+-------------+---+
-| all-to-idle | 3 |
-+-------------+---+
++----------------+---+
+| no-change | 0 |
++----------------+---+
+| rt-to-be | 2 |
++----------------+---+
+| all-to-idle | 3 |
++----------------+---+
The numerical value that corresponds to each I/O priority class is as follows:
@@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
The algorithm to set the I/O priority class for a request is as follows:
-- Translate the I/O priority class policy into a number.
-- Change the request I/O priority class into the maximum of the I/O priority
- class policy number and the numerical I/O priority class.
+- If I/O priority class policy is promote-to-rt, change the request I/O
+ priority class to IOPRIO_CLASS_RT and change the request I/O priority
+ level to 4.
+- If I/O priorityt class is not promote-to-rt, translate the I/O priority
+ class policy into a number, then change the request I/O priority class
+ into the maximum of the I/O priority class policy number and the numerical
+ I/O priority class.
PID
---
diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
index 055529b9b92b..4051fada01f1 100644
--- a/block/blk-ioprio.c
+++ b/block/blk-ioprio.c
@@ -23,25 +23,28 @@
/**
* enum prio_policy - I/O priority class policy.
* @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
- * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
+ * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT.
* @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
* IOPRIO_CLASS_BE.
* @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
+ * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT.
*
* See also <linux/ioprio.h>.
*/
enum prio_policy {
POLICY_NO_CHANGE = 0,
- POLICY_NONE_TO_RT = 1,
+ POLICY_PROMOTE_TO_RT = 1,
POLICY_RESTRICT_TO_BE = 2,
POLICY_ALL_TO_IDLE = 3,
+ POLICY_NONE_TO_RT = 4,
};
static const char *policy_name[] = {
[POLICY_NO_CHANGE] = "no-change",
- [POLICY_NONE_TO_RT] = "none-to-rt",
+ [POLICY_PROMOTE_TO_RT] = "promote-to-rt",
[POLICY_RESTRICT_TO_BE] = "restrict-to-be",
[POLICY_ALL_TO_IDLE] = "idle",
+ [POLICY_NONE_TO_RT] = "none-to-rt",
};
static struct blkcg_policy ioprio_policy;
@@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio)
if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)
return;
+ if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT ||
+ blkcg->prio_policy == POLICY_NONE_TO_RT) {
+ /*
+ * For RT threads, the default priority level is 4 because
+ * task_nice is 0. By promoting non-RT io-priority to RT-class
+ * and default level 4, those requests that are already
+ * RT-class but need a higher io-priority can use ioprio_set()
+ * to achieve this.
+ */
+ if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT)
+ bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4);
+ return;
+ }
+
/*
* Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
* correspond to a lower priority. Hence, the max_t() below selects
--
2.29.2
On 4/28/23 14:44, Hou Tao wrote:
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index f67c0829350b..7544ce00e0cb 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -2024,31 +2024,33 @@ that attribute:
> no-change
> Do not modify the I/O priority class.
>
> - none-to-rt
> - For requests that do not have an I/O priority class (NONE),
> - change the I/O priority class into RT. Do not modify
> - the I/O priority class of other requests.
> + promote-to-rt
> + For requests that have a non-RT I/O priority class, change it into RT.
> + Also change the priority level of these requests to 4. Do not modify
> + the I/O priority of requests that have priority class RT.
>
> restrict-to-be
> For requests that do not have an I/O priority class or that have I/O
> - priority class RT, change it into BE. Do not modify the I/O priority
> - class of requests that have priority class IDLE.
> + priority class RT, change it into BE. Also change the priority level
> + of these requests to 0. Do not modify the I/O priority class of
> + requests that have priority class IDLE.
>
> idle
> Change the I/O priority class of all requests into IDLE, the lowest
> I/O priority class.
>
> + none-to-rt
> + Deprecated. Just an alias for promote-to-rt.
> +
> The following numerical values are associated with the I/O priority policies:
>
> -+-------------+---+
> -| no-change | 0 |
> -+-------------+---+
> -| none-to-rt | 1 |
> -+-------------+---+
> -| rt-to-be | 2 |
> -+-------------+---+
> -| all-to-idle | 3 |
> -+-------------+---+
> ++----------------+---+
> +| no-change | 0 |
> ++----------------+---+
> +| rt-to-be | 2 |
> ++----------------+---+
> +| all-to-idle | 3 |
> ++----------------+---+
>
> The numerical value that corresponds to each I/O priority class is as follows:
>
> @@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
>
> The algorithm to set the I/O priority class for a request is as follows:
>
> -- Translate the I/O priority class policy into a number.
> -- Change the request I/O priority class into the maximum of the I/O priority
> - class policy number and the numerical I/O priority class.
> +- If I/O priority class policy is promote-to-rt, change the request I/O
> + priority class to IOPRIO_CLASS_RT and change the request I/O priority
> + level to 4.
> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority
> + class policy into a number, then change the request I/O priority class
> + into the maximum of the I/O priority class policy number and the numerical
> + I/O priority class.
>
> PID
> ---
The doc LGTM, thanks!
Reviewed-by: Bagas Sanjaya <[email protected]>
--
An old man doll... just what I always wanted! - Clara
ping ?
On 4/28/2023 3:44 PM, Hou Tao wrote:
> From: Hou Tao <[email protected]>
>
> Since commit a78418e6a04c ("block: Always initialize bio IO priority on
> submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
> blkcg_set_ioprio(), so there will be no way to promote the io-priority
> of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
> greater than or equals to IOPRIO_CLASS_RT.
>
> It seems possible to call blkcg_set_ioprio() first then try to
> initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
> for bio in which bi_ioprio is already initialized (e.g., direct-io), so
> introduce a new promote-to-rt policy to promote the iopriority of bio to
> IOPRIO_CLASS_RT if the ioprio is not already RT.
>
> For none-to-rt policy, although it doesn't work now, but considering
> that its purpose was also to override the io-priority to RT and allowing
> for a smoother transition, just keep it and treat it as an alias of
> the promote-to-rt policy.
>
> Acked-by: Tejun Heo <[email protected]>
> Reviewed-by: Bart Van Assche <[email protected]>
> Reviewed-by: Chaitanya Kulkarni <[email protected]>
> Reviewed-by: Jan Kara <[email protected]>
> Signed-off-by: Hou Tao <[email protected]>
> ---
> v4:
> * rebased on 33afd4b76393
> * Add Reviewed-by from Jan Kara
>
> v3: https://lore.kernel.org/linux-block/[email protected]
> * Use 'non-RT' instead of 'no-RT' in document (from Bagas)
> * Remove repeated sentence in commit message
> * Add Reviewed-by and Acked-by tags
>
> v2: https://lore.kernel.org/linux-block/[email protected]
>
> * Simplify the implementation of promote-to-rt (from Bart)
> * Make none-to-rt to work again by treating it as an alias of
> the promote-to-rt policy (from Bart & Jan)
> * fix the style of new content in cgroup-v2.rst (from Bagas)
> * set the default priority level to 4 instead of 0 for promote-to-rt
>
> v1: https://lore.kernel.org/linux-block/[email protected]
>
> Documentation/admin-guide/cgroup-v2.rst | 42 ++++++++++++++-----------
> block/blk-ioprio.c | 23 ++++++++++++--
> 2 files changed, 44 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index f67c0829350b..7544ce00e0cb 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -2024,31 +2024,33 @@ that attribute:
> no-change
> Do not modify the I/O priority class.
>
> - none-to-rt
> - For requests that do not have an I/O priority class (NONE),
> - change the I/O priority class into RT. Do not modify
> - the I/O priority class of other requests.
> + promote-to-rt
> + For requests that have a non-RT I/O priority class, change it into RT.
> + Also change the priority level of these requests to 4. Do not modify
> + the I/O priority of requests that have priority class RT.
>
> restrict-to-be
> For requests that do not have an I/O priority class or that have I/O
> - priority class RT, change it into BE. Do not modify the I/O priority
> - class of requests that have priority class IDLE.
> + priority class RT, change it into BE. Also change the priority level
> + of these requests to 0. Do not modify the I/O priority class of
> + requests that have priority class IDLE.
>
> idle
> Change the I/O priority class of all requests into IDLE, the lowest
> I/O priority class.
>
> + none-to-rt
> + Deprecated. Just an alias for promote-to-rt.
> +
> The following numerical values are associated with the I/O priority policies:
>
> -+-------------+---+
> -| no-change | 0 |
> -+-------------+---+
> -| none-to-rt | 1 |
> -+-------------+---+
> -| rt-to-be | 2 |
> -+-------------+---+
> -| all-to-idle | 3 |
> -+-------------+---+
> ++----------------+---+
> +| no-change | 0 |
> ++----------------+---+
> +| rt-to-be | 2 |
> ++----------------+---+
> +| all-to-idle | 3 |
> ++----------------+---+
>
> The numerical value that corresponds to each I/O priority class is as follows:
>
> @@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
>
> The algorithm to set the I/O priority class for a request is as follows:
>
> -- Translate the I/O priority class policy into a number.
> -- Change the request I/O priority class into the maximum of the I/O priority
> - class policy number and the numerical I/O priority class.
> +- If I/O priority class policy is promote-to-rt, change the request I/O
> + priority class to IOPRIO_CLASS_RT and change the request I/O priority
> + level to 4.
> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority
> + class policy into a number, then change the request I/O priority class
> + into the maximum of the I/O priority class policy number and the numerical
> + I/O priority class.
>
> PID
> ---
> diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
> index 055529b9b92b..4051fada01f1 100644
> --- a/block/blk-ioprio.c
> +++ b/block/blk-ioprio.c
> @@ -23,25 +23,28 @@
> /**
> * enum prio_policy - I/O priority class policy.
> * @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
> - * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
> + * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT.
> * @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
> * IOPRIO_CLASS_BE.
> * @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
> + * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT.
> *
> * See also <linux/ioprio.h>.
> */
> enum prio_policy {
> POLICY_NO_CHANGE = 0,
> - POLICY_NONE_TO_RT = 1,
> + POLICY_PROMOTE_TO_RT = 1,
> POLICY_RESTRICT_TO_BE = 2,
> POLICY_ALL_TO_IDLE = 3,
> + POLICY_NONE_TO_RT = 4,
> };
>
> static const char *policy_name[] = {
> [POLICY_NO_CHANGE] = "no-change",
> - [POLICY_NONE_TO_RT] = "none-to-rt",
> + [POLICY_PROMOTE_TO_RT] = "promote-to-rt",
> [POLICY_RESTRICT_TO_BE] = "restrict-to-be",
> [POLICY_ALL_TO_IDLE] = "idle",
> + [POLICY_NONE_TO_RT] = "none-to-rt",
> };
>
> static struct blkcg_policy ioprio_policy;
> @@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio)
> if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)
> return;
>
> + if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT ||
> + blkcg->prio_policy == POLICY_NONE_TO_RT) {
> + /*
> + * For RT threads, the default priority level is 4 because
> + * task_nice is 0. By promoting non-RT io-priority to RT-class
> + * and default level 4, those requests that are already
> + * RT-class but need a higher io-priority can use ioprio_set()
> + * to achieve this.
> + */
> + if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT)
> + bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4);
> + return;
> + }
> +
> /*
> * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
> * correspond to a lower priority. Hence, the max_t() below selects
ping ?
On 5/8/2023 8:08 PM, Hou Tao wrote:
> ping ?
>
> On 4/28/2023 3:44 PM, Hou Tao wrote:
>> From: Hou Tao <[email protected]>
>>
>> Since commit a78418e6a04c ("block: Always initialize bio IO priority on
>> submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
>> blkcg_set_ioprio(), so there will be no way to promote the io-priority
>> of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
>> greater than or equals to IOPRIO_CLASS_RT.
>>
>> It seems possible to call blkcg_set_ioprio() first then try to
>> initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
>> for bio in which bi_ioprio is already initialized (e.g., direct-io), so
>> introduce a new promote-to-rt policy to promote the iopriority of bio to
>> IOPRIO_CLASS_RT if the ioprio is not already RT.
>>
>> For none-to-rt policy, although it doesn't work now, but considering
>> that its purpose was also to override the io-priority to RT and allowing
>> for a smoother transition, just keep it and treat it as an alias of
>> the promote-to-rt policy.
>>
>> Acked-by: Tejun Heo <[email protected]>
>> Reviewed-by: Bart Van Assche <[email protected]>
>> Reviewed-by: Chaitanya Kulkarni <[email protected]>
>> Reviewed-by: Jan Kara <[email protected]>
>> Signed-off-by: Hou Tao <[email protected]>
>> ---
>> v4:
>> * rebased on 33afd4b76393
>> * Add Reviewed-by from Jan Kara
>>
>> v3: https://lore.kernel.org/linux-block/[email protected]
>> * Use 'non-RT' instead of 'no-RT' in document (from Bagas)
>> * Remove repeated sentence in commit message
>> * Add Reviewed-by and Acked-by tags
>>
>> v2: https://lore.kernel.org/linux-block/[email protected]
>>
>> * Simplify the implementation of promote-to-rt (from Bart)
>> * Make none-to-rt to work again by treating it as an alias of
>> the promote-to-rt policy (from Bart & Jan)
>> * fix the style of new content in cgroup-v2.rst (from Bagas)
>> * set the default priority level to 4 instead of 0 for promote-to-rt
>>
>> v1: https://lore.kernel.org/linux-block/[email protected]
>>
>> Documentation/admin-guide/cgroup-v2.rst | 42 ++++++++++++++-----------
>> block/blk-ioprio.c | 23 ++++++++++++--
>> 2 files changed, 44 insertions(+), 21 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
>> index f67c0829350b..7544ce00e0cb 100644
>> --- a/Documentation/admin-guide/cgroup-v2.rst
>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>> @@ -2024,31 +2024,33 @@ that attribute:
>> no-change
>> Do not modify the I/O priority class.
>>
>> - none-to-rt
>> - For requests that do not have an I/O priority class (NONE),
>> - change the I/O priority class into RT. Do not modify
>> - the I/O priority class of other requests.
>> + promote-to-rt
>> + For requests that have a non-RT I/O priority class, change it into RT.
>> + Also change the priority level of these requests to 4. Do not modify
>> + the I/O priority of requests that have priority class RT.
>>
>> restrict-to-be
>> For requests that do not have an I/O priority class or that have I/O
>> - priority class RT, change it into BE. Do not modify the I/O priority
>> - class of requests that have priority class IDLE.
>> + priority class RT, change it into BE. Also change the priority level
>> + of these requests to 0. Do not modify the I/O priority class of
>> + requests that have priority class IDLE.
>>
>> idle
>> Change the I/O priority class of all requests into IDLE, the lowest
>> I/O priority class.
>>
>> + none-to-rt
>> + Deprecated. Just an alias for promote-to-rt.
>> +
>> The following numerical values are associated with the I/O priority policies:
>>
>> -+-------------+---+
>> -| no-change | 0 |
>> -+-------------+---+
>> -| none-to-rt | 1 |
>> -+-------------+---+
>> -| rt-to-be | 2 |
>> -+-------------+---+
>> -| all-to-idle | 3 |
>> -+-------------+---+
>> ++----------------+---+
>> +| no-change | 0 |
>> ++----------------+---+
>> +| rt-to-be | 2 |
>> ++----------------+---+
>> +| all-to-idle | 3 |
>> ++----------------+---+
>>
>> The numerical value that corresponds to each I/O priority class is as follows:
>>
>> @@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
>>
>> The algorithm to set the I/O priority class for a request is as follows:
>>
>> -- Translate the I/O priority class policy into a number.
>> -- Change the request I/O priority class into the maximum of the I/O priority
>> - class policy number and the numerical I/O priority class.
>> +- If I/O priority class policy is promote-to-rt, change the request I/O
>> + priority class to IOPRIO_CLASS_RT and change the request I/O priority
>> + level to 4.
>> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority
>> + class policy into a number, then change the request I/O priority class
>> + into the maximum of the I/O priority class policy number and the numerical
>> + I/O priority class.
>>
>> PID
>> ---
>> diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
>> index 055529b9b92b..4051fada01f1 100644
>> --- a/block/blk-ioprio.c
>> +++ b/block/blk-ioprio.c
>> @@ -23,25 +23,28 @@
>> /**
>> * enum prio_policy - I/O priority class policy.
>> * @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
>> - * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
>> + * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT.
>> * @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
>> * IOPRIO_CLASS_BE.
>> * @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
>> + * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT.
>> *
>> * See also <linux/ioprio.h>.
>> */
>> enum prio_policy {
>> POLICY_NO_CHANGE = 0,
>> - POLICY_NONE_TO_RT = 1,
>> + POLICY_PROMOTE_TO_RT = 1,
>> POLICY_RESTRICT_TO_BE = 2,
>> POLICY_ALL_TO_IDLE = 3,
>> + POLICY_NONE_TO_RT = 4,
>> };
>>
>> static const char *policy_name[] = {
>> [POLICY_NO_CHANGE] = "no-change",
>> - [POLICY_NONE_TO_RT] = "none-to-rt",
>> + [POLICY_PROMOTE_TO_RT] = "promote-to-rt",
>> [POLICY_RESTRICT_TO_BE] = "restrict-to-be",
>> [POLICY_ALL_TO_IDLE] = "idle",
>> + [POLICY_NONE_TO_RT] = "none-to-rt",
>> };
>>
>> static struct blkcg_policy ioprio_policy;
>> @@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio)
>> if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)
>> return;
>>
>> + if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT ||
>> + blkcg->prio_policy == POLICY_NONE_TO_RT) {
>> + /*
>> + * For RT threads, the default priority level is 4 because
>> + * task_nice is 0. By promoting non-RT io-priority to RT-class
>> + * and default level 4, those requests that are already
>> + * RT-class but need a higher io-priority can use ioprio_set()
>> + * to achieve this.
>> + */
>> + if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT)
>> + bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4);
>> + return;
>> + }
>> +
>> /*
>> * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
>> * correspond to a lower priority. Hence, the max_t() below selects
> .
ping ?
On 5/23/2023 2:48 PM, Hou Tao wrote:
> ping ?
>
> On 5/8/2023 8:08 PM, Hou Tao wrote:
>> ping ?
>>
>> On 4/28/2023 3:44 PM, Hou Tao wrote:
>>> From: Hou Tao <[email protected]>
>>>
>>> Since commit a78418e6a04c ("block: Always initialize bio IO priority on
>>> submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
>>> blkcg_set_ioprio(), so there will be no way to promote the io-priority
>>> of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
>>> greater than or equals to IOPRIO_CLASS_RT.
>>>
>>> It seems possible to call blkcg_set_ioprio() first then try to
>>> initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
>>> for bio in which bi_ioprio is already initialized (e.g., direct-io), so
>>> introduce a new promote-to-rt policy to promote the iopriority of bio to
>>> IOPRIO_CLASS_RT if the ioprio is not already RT.
>>>
>>> For none-to-rt policy, although it doesn't work now, but considering
>>> that its purpose was also to override the io-priority to RT and allowing
>>> for a smoother transition, just keep it and treat it as an alias of
>>> the promote-to-rt policy.
>>>
>>> Acked-by: Tejun Heo <[email protected]>
>>> Reviewed-by: Bart Van Assche <[email protected]>
>>> Reviewed-by: Chaitanya Kulkarni <[email protected]>
>>> Reviewed-by: Jan Kara <[email protected]>
>>> Signed-off-by: Hou Tao <[email protected]>
>>> ---
>>> v4:
>>> * rebased on 33afd4b76393
>>> * Add Reviewed-by from Jan Kara
>>>
>>> v3: https://lore.kernel.org/linux-block/[email protected]
>>> * Use 'non-RT' instead of 'no-RT' in document (from Bagas)
>>> * Remove repeated sentence in commit message
>>> * Add Reviewed-by and Acked-by tags
>>>
>>> v2: https://lore.kernel.org/linux-block/[email protected]
>>>
>>> * Simplify the implementation of promote-to-rt (from Bart)
>>> * Make none-to-rt to work again by treating it as an alias of
>>> the promote-to-rt policy (from Bart & Jan)
>>> * fix the style of new content in cgroup-v2.rst (from Bagas)
>>> * set the default priority level to 4 instead of 0 for promote-to-rt
>>>
>>> v1: https://lore.kernel.org/linux-block/[email protected]
>>>
>>> Documentation/admin-guide/cgroup-v2.rst | 42 ++++++++++++++-----------
>>> block/blk-ioprio.c | 23 ++++++++++++--
>>> 2 files changed, 44 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
>>> index f67c0829350b..7544ce00e0cb 100644
>>> --- a/Documentation/admin-guide/cgroup-v2.rst
>>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>>> @@ -2024,31 +2024,33 @@ that attribute:
>>> no-change
>>> Do not modify the I/O priority class.
>>>
>>> - none-to-rt
>>> - For requests that do not have an I/O priority class (NONE),
>>> - change the I/O priority class into RT. Do not modify
>>> - the I/O priority class of other requests.
>>> + promote-to-rt
>>> + For requests that have a non-RT I/O priority class, change it into RT.
>>> + Also change the priority level of these requests to 4. Do not modify
>>> + the I/O priority of requests that have priority class RT.
>>>
>>> restrict-to-be
>>> For requests that do not have an I/O priority class or that have I/O
>>> - priority class RT, change it into BE. Do not modify the I/O priority
>>> - class of requests that have priority class IDLE.
>>> + priority class RT, change it into BE. Also change the priority level
>>> + of these requests to 0. Do not modify the I/O priority class of
>>> + requests that have priority class IDLE.
>>>
>>> idle
>>> Change the I/O priority class of all requests into IDLE, the lowest
>>> I/O priority class.
>>>
>>> + none-to-rt
>>> + Deprecated. Just an alias for promote-to-rt.
>>> +
>>> The following numerical values are associated with the I/O priority policies:
>>>
>>> -+-------------+---+
>>> -| no-change | 0 |
>>> -+-------------+---+
>>> -| none-to-rt | 1 |
>>> -+-------------+---+
>>> -| rt-to-be | 2 |
>>> -+-------------+---+
>>> -| all-to-idle | 3 |
>>> -+-------------+---+
>>> ++----------------+---+
>>> +| no-change | 0 |
>>> ++----------------+---+
>>> +| rt-to-be | 2 |
>>> ++----------------+---+
>>> +| all-to-idle | 3 |
>>> ++----------------+---+
>>>
>>> The numerical value that corresponds to each I/O priority class is as follows:
>>>
>>> @@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
>>>
>>> The algorithm to set the I/O priority class for a request is as follows:
>>>
>>> -- Translate the I/O priority class policy into a number.
>>> -- Change the request I/O priority class into the maximum of the I/O priority
>>> - class policy number and the numerical I/O priority class.
>>> +- If I/O priority class policy is promote-to-rt, change the request I/O
>>> + priority class to IOPRIO_CLASS_RT and change the request I/O priority
>>> + level to 4.
>>> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority
>>> + class policy into a number, then change the request I/O priority class
>>> + into the maximum of the I/O priority class policy number and the numerical
>>> + I/O priority class.
>>>
>>> PID
>>> ---
>>> diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
>>> index 055529b9b92b..4051fada01f1 100644
>>> --- a/block/blk-ioprio.c
>>> +++ b/block/blk-ioprio.c
>>> @@ -23,25 +23,28 @@
>>> /**
>>> * enum prio_policy - I/O priority class policy.
>>> * @POLICY_NO_CHANGE: (default) do not modify the I/O priority class.
>>> - * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT.
>>> + * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT.
>>> * @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into
>>> * IOPRIO_CLASS_BE.
>>> * @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE.
>>> + * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT.
>>> *
>>> * See also <linux/ioprio.h>.
>>> */
>>> enum prio_policy {
>>> POLICY_NO_CHANGE = 0,
>>> - POLICY_NONE_TO_RT = 1,
>>> + POLICY_PROMOTE_TO_RT = 1,
>>> POLICY_RESTRICT_TO_BE = 2,
>>> POLICY_ALL_TO_IDLE = 3,
>>> + POLICY_NONE_TO_RT = 4,
>>> };
>>>
>>> static const char *policy_name[] = {
>>> [POLICY_NO_CHANGE] = "no-change",
>>> - [POLICY_NONE_TO_RT] = "none-to-rt",
>>> + [POLICY_PROMOTE_TO_RT] = "promote-to-rt",
>>> [POLICY_RESTRICT_TO_BE] = "restrict-to-be",
>>> [POLICY_ALL_TO_IDLE] = "idle",
>>> + [POLICY_NONE_TO_RT] = "none-to-rt",
>>> };
>>>
>>> static struct blkcg_policy ioprio_policy;
>>> @@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio)
>>> if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)
>>> return;
>>>
>>> + if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT ||
>>> + blkcg->prio_policy == POLICY_NONE_TO_RT) {
>>> + /*
>>> + * For RT threads, the default priority level is 4 because
>>> + * task_nice is 0. By promoting non-RT io-priority to RT-class
>>> + * and default level 4, those requests that are already
>>> + * RT-class but need a higher io-priority can use ioprio_set()
>>> + * to achieve this.
>>> + */
>>> + if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT)
>>> + bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4);
>>> + return;
>>> + }
>>> +
>>> /*
>>> * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers
>>> * correspond to a lower priority. Hence, the max_t() below selects
>> .
> .
On Fri, 28 Apr 2023 15:44:04 +0800, Hou Tao wrote:
> Since commit a78418e6a04c ("block: Always initialize bio IO priority on
> submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
> blkcg_set_ioprio(), so there will be no way to promote the io-priority
> of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
> greater than or equals to IOPRIO_CLASS_RT.
>
> It seems possible to call blkcg_set_ioprio() first then try to
> initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
> for bio in which bi_ioprio is already initialized (e.g., direct-io), so
> introduce a new promote-to-rt policy to promote the iopriority of bio to
> IOPRIO_CLASS_RT if the ioprio is not already RT.
>
> [...]
Applied, thanks!
[1/1] blk-ioprio: Introduce promote-to-rt policy
commit: ddf63516d8d37528dc6834c7f19b55084e956068
Best regards,
--
Jens Axboe