After a call to io_submit_sqe(), it's already known whether it needs
to queue a link or not. Do it there, as it's simplier and doesn't keep
an extra variable across the loop.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index ebe2a4edd644..82c2da99cb5c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
struct io_submit_state state, *statep = NULL;
struct io_kiocb *link = NULL;
struct io_kiocb *shadow_req = NULL;
- bool prev_was_link = false;
int i, submitted = 0;
bool mm_fault = false;
@@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
}
}
- /*
- * If previous wasn't linked and we have a linked command,
- * that's the end of the chain. Submit the previous link.
- */
- if (!prev_was_link && link) {
- io_queue_link_head(ctx, link, &link->submit, shadow_req);
- link = NULL;
- shadow_req = NULL;
- }
- prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
-
if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
if (!shadow_req) {
shadow_req = io_get_req(ctx, NULL);
@@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
io_submit_sqe(ctx, &s, statep, &link);
submitted++;
+
+ /*
+ * If previous wasn't linked and we have a linked command,
+ * that's the end of the chain. Submit the previous link.
+ */
+ if (!(s.sqe->flags & IOSQE_IO_LINK) && link) {
+ io_queue_link_head(ctx, link, &link->submit, shadow_req);
+ link = NULL;
+ shadow_req = NULL;
+ }
}
if (link)
--
2.23.0
On 11/6/19 5:22 AM, Pavel Begunkov wrote:
> After a call to io_submit_sqe(), it's already known whether it needs
> to queue a link or not. Do it there, as it's simplier and doesn't keep
> an extra variable across the loop.
>
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
> fs/io_uring.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index ebe2a4edd644..82c2da99cb5c 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> struct io_submit_state state, *statep = NULL;
> struct io_kiocb *link = NULL;
> struct io_kiocb *shadow_req = NULL;
> - bool prev_was_link = false;
> int i, submitted = 0;
> bool mm_fault = false;
>
> @@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> }
> }
>
> - /*
> - * If previous wasn't linked and we have a linked command,
> - * that's the end of the chain. Submit the previous link.
> - */
> - if (!prev_was_link && link) {
> - io_queue_link_head(ctx, link, &link->submit, shadow_req);
> - link = NULL;
> - shadow_req = NULL;
> - }
> - prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
> -
> if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
> if (!shadow_req) {
> shadow_req = io_get_req(ctx, NULL);
> @@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
> trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
> io_submit_sqe(ctx, &s, statep, &link);
> submitted++;
> +
> + /*
> + * If previous wasn't linked and we have a linked command,
> + * that's the end of the chain. Submit the previous link.
> + */
> + if (!(s.sqe->flags & IOSQE_IO_LINK) && link)
The behavior changed to 'current seq' instead of previous after dropping prev_was_link?
> + io_queue_link_head(ctx, link, &link->submit, shadow_req);
> + link = NULL;
> + shadow_req = NULL;
> + }
> }
>
> if (link)
>
On 11/6/2019 11:36 AM, Bob Liu wrote:
> On 11/6/19 5:22 AM, Pavel Begunkov wrote:
>> After a call to io_submit_sqe(), it's already known whether it needs
>> to queue a link or not. Do it there, as it's simplier and doesn't keep
>> an extra variable across the loop.
>>
>> Signed-off-by: Pavel Begunkov <[email protected]>
>> ---
>> fs/io_uring.c | 22 ++++++++++------------
>> 1 file changed, 10 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index ebe2a4edd644..82c2da99cb5c 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>> struct io_submit_state state, *statep = NULL;
>> struct io_kiocb *link = NULL;
>> struct io_kiocb *shadow_req = NULL;
>> - bool prev_was_link = false;
>> int i, submitted = 0;
>> bool mm_fault = false;
>>
>> @@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>> }
>> }
>>
>> - /*
>> - * If previous wasn't linked and we have a linked command,
>> - * that's the end of the chain. Submit the previous link.
>> - */
>> - if (!prev_was_link && link) {
>> - io_queue_link_head(ctx, link, &link->submit, shadow_req);
>> - link = NULL;
>> - shadow_req = NULL;
>> - }
>> - prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
>> -
>> if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
>> if (!shadow_req) {
>> shadow_req = io_get_req(ctx, NULL);
>> @@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>> trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
>> io_submit_sqe(ctx, &s, statep, &link);
>> submitted++;
>> +
>> + /*
>> + * If previous wasn't linked and we have a linked command,
>> + * that's the end of the chain. Submit the previous link.
>> + */
>> + if (!(s.sqe->flags & IOSQE_IO_LINK) && link)
> The behavior changed to 'current seq' instead of previous after dropping prev_was_link?
>
The old behaviour was to remember @prev_was_link for current sqe, and
use at the beginning of the next iteration, where it becomes
"previous/last sqe". See, prev_was_link was set after io_queue_link_head.
If @i is iteration idx, then timeline was:
i: sqe[i-1].is_link -> io_queue_link_head() # if (prev_was_link)
i: sqe[i].is_link = prev_was_link = (sqe[i].flags & LINK)
i+1: sqe[i].is_link -> io_queue_link_head() # if (prev_was_link)
i+1: sqe[i+1].is_link = ...
After the change, it's done at the same loop iteration by swapping order
of checking @prev_was_link and io_queue_link_head().
i: sqe[i].is_link = ...
i: sqe[i].is_link -> io_queue_link_head()
i+1: sqe[i+1].is_link = ...
i+1: sqe[i+1].is_link -> io_queue_link_head()
Shouldn't change the behavior, if I'm not missing something.
>> + io_queue_link_head(ctx, link, &link->submit, shadow_req);
>> + link = NULL;
>> + shadow_req = NULL;
>> + }
>> }
>>
>> if (link)
>>
>
On 11/6/2019 12:06 PM, Pavel Begunkov wrote:
> On 11/6/2019 11:36 AM, Bob Liu wrote:
>> On 11/6/19 5:22 AM, Pavel Begunkov wrote:
>>> After a call to io_submit_sqe(), it's already known whether it needs
>>> to queue a link or not. Do it there, as it's simplier and doesn't keep
>>> an extra variable across the loop.
>>>
>>> Signed-off-by: Pavel Begunkov <[email protected]>
>>> ---
>>> fs/io_uring.c | 22 ++++++++++------------
>>> 1 file changed, 10 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index ebe2a4edd644..82c2da99cb5c 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>> struct io_submit_state state, *statep = NULL;
>>> struct io_kiocb *link = NULL;
>>> struct io_kiocb *shadow_req = NULL;
>>> - bool prev_was_link = false;
>>> int i, submitted = 0;
>>> bool mm_fault = false;
>>>
>>> @@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>> }
>>> }
>>>
>>> - /*
>>> - * If previous wasn't linked and we have a linked command,
>>> - * that's the end of the chain. Submit the previous link.
>>> - */
>>> - if (!prev_was_link && link) {
>>> - io_queue_link_head(ctx, link, &link->submit, shadow_req);
>>> - link = NULL;
>>> - shadow_req = NULL;
>>> - }
>>> - prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
>>> -
>>> if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
>>> if (!shadow_req) {
>>> shadow_req = io_get_req(ctx, NULL);
>>> @@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>> trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
>>> io_submit_sqe(ctx, &s, statep, &link);
>>> submitted++;
>>> +
>>> + /*
>>> + * If previous wasn't linked and we have a linked command,
>>> + * that's the end of the chain. Submit the previous link.
>>> + */
>>> + if (!(s.sqe->flags & IOSQE_IO_LINK) && link)
>> The behavior changed to 'current seq' instead of previous after dropping prev_was_link?
>>
> The old behaviour was to remember @prev_was_link for current sqe, and
> use at the beginning of the next iteration, where it becomes
> "previous/last sqe". See, prev_was_link was set after io_queue_link_head.
>
> If @i is iteration idx, then timeline was:
> i: sqe[i-1].is_link -> io_queue_link_head() # if (prev_was_link)
> i: sqe[i].is_link = prev_was_link = (sqe[i].flags & LINK)
> i+1: sqe[i].is_link -> io_queue_link_head() # if (prev_was_link)
> i+1: sqe[i+1].is_link = ...
>
>
> After the change, it's done at the same loop iteration by swapping order
> of checking @prev_was_link and io_queue_link_head().
>
> i: sqe[i].is_link = ...
> i: sqe[i].is_link -> io_queue_link_head()
> i+1: sqe[i+1].is_link = ...
> i+1: sqe[i+1].is_link -> io_queue_link_head()
>
> Shouldn't change the behavior, if I'm not missing something.
>
And the same goes for ordering with io_submit_sqe(), which assembles a link.
i: prev_was_link = ... # for sqe[i]
i: io_submit_sqe() # for sqe[i]
i+1: prev_was_link -> io_queue_link_head # for sqe[i]
after:
i: io_submit_sqe() # for sqe[i]
i: is_link = ... # for sqe[i]
i: is_link -> io_queue_link_head # for sqe[i]
>
>>> + io_queue_link_head(ctx, link, &link->submit, shadow_req);
>>> + link = NULL;
>>> + shadow_req = NULL;
>>> + }
>>> }
>>>
>>> if (link)
>>>
>>
On 11/6/19 5:31 PM, Pavel Begunkov wrote:
> On 11/6/2019 12:06 PM, Pavel Begunkov wrote:
>> On 11/6/2019 11:36 AM, Bob Liu wrote:
>>> On 11/6/19 5:22 AM, Pavel Begunkov wrote:
>>>> After a call to io_submit_sqe(), it's already known whether it needs
>>>> to queue a link or not. Do it there, as it's simplier and doesn't keep
>>>> an extra variable across the loop.
>>>>
>>>> Signed-off-by: Pavel Begunkov <[email protected]>
>>>> ---
>>>> fs/io_uring.c | 22 ++++++++++------------
>>>> 1 file changed, 10 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>>> index ebe2a4edd644..82c2da99cb5c 100644
>>>> --- a/fs/io_uring.c
>>>> +++ b/fs/io_uring.c
>>>> @@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>>> struct io_submit_state state, *statep = NULL;
>>>> struct io_kiocb *link = NULL;
>>>> struct io_kiocb *shadow_req = NULL;
>>>> - bool prev_was_link = false;
>>>> int i, submitted = 0;
>>>> bool mm_fault = false;
>>>>
>>>> @@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>>> }
>>>> }
>>>>
>>>> - /*
>>>> - * If previous wasn't linked and we have a linked command,
>>>> - * that's the end of the chain. Submit the previous link.
>>>> - */
>>>> - if (!prev_was_link && link) {
>>>> - io_queue_link_head(ctx, link, &link->submit, shadow_req);
>>>> - link = NULL;
>>>> - shadow_req = NULL;
>>>> - }
>>>> - prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
>>>> -
>>>> if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
>>>> if (!shadow_req) {
>>>> shadow_req = io_get_req(ctx, NULL);
>>>> @@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
>>>> trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
>>>> io_submit_sqe(ctx, &s, statep, &link);
>>>> submitted++;
>>>> +
>>>> + /*
>>>> + * If previous wasn't linked and we have a linked command,
>>>> + * that's the end of the chain. Submit the previous link.
>>>> + */
>>>> + if (!(s.sqe->flags & IOSQE_IO_LINK) && link)
>>> The behavior changed to 'current seq' instead of previous after dropping prev_was_link?
>>>
>> The old behaviour was to remember @prev_was_link for current sqe, and
>> use at the beginning of the next iteration, where it becomes
>> "previous/last sqe". See, prev_was_link was set after io_queue_link_head.
>>
>> If @i is iteration idx, then timeline was:
>> i: sqe[i-1].is_link -> io_queue_link_head() # if (prev_was_link)
>> i: sqe[i].is_link = prev_was_link = (sqe[i].flags & LINK)
>> i+1: sqe[i].is_link -> io_queue_link_head() # if (prev_was_link)
>> i+1: sqe[i+1].is_link = ...
>>
>>
>> After the change, it's done at the same loop iteration by swapping order
>> of checking @prev_was_link and io_queue_link_head().
>>
>> i: sqe[i].is_link = ...
>> i: sqe[i].is_link -> io_queue_link_head()
>> i+1: sqe[i+1].is_link = ...
>> i+1: sqe[i+1].is_link -> io_queue_link_head()
>>
>> Shouldn't change the behavior, if I'm not missing something.
>>
> And the same goes for ordering with io_submit_sqe(), which assembles a link.
>
> i: prev_was_link = ... # for sqe[i]
> i: io_submit_sqe() # for sqe[i]
> i+1: prev_was_link -> io_queue_link_head # for sqe[i]
>
> after:
> i: io_submit_sqe() # for sqe[i]
> i: is_link = ... # for sqe[i]
> i: is_link -> io_queue_link_head # for sqe[i]
>
I see, sorry for the noise.
Reviewed-by： Bob Liu <[email protected]>
>>
>>>> + io_queue_link_head(ctx, link, &link->submit, shadow_req);
>>>> + link = NULL;
>>>> + shadow_req = NULL;
>>>> + }
>>>> }
>>>>
>>>> if (link)
>>>>
>>>