2018-03-06 11:55:22

by Yisheng Xie

Subject: [PATCH] perf mmap: Discard head in overwrite_rb_find_range

In overwrite mode, start will be set to head in perf_mmap__read_init.
Therefore, it is no need to set the start one more in
overwrite_rb_find_range and *start can be used as head instead of
passing head to overwrite_rb_find_range.

Signed-off-by: Yisheng Xie <[email protected]>
---
tools/perf/util/mmap.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 91531a7..6751ac9 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
return 0;
}

-static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
+static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
{
struct perf_event_header *pheader;
- u64 evt_head = head;
+ u64 evt_head = *start;
int size = mask + 1;

- pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
- pheader = (struct perf_event_header *)(buf + (head & mask));
- *start = head;
+ pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
+ pheader = (struct perf_event_header *)(buf + (*start & mask));
while (true) {
- if (evt_head - head >= (unsigned int)size) {
+ if (evt_head - *start >= (unsigned int)size) {
pr_debug("Finished reading overwrite ring buffer: rewind\n");
- if (evt_head - head > (unsigned int)size)
+ if (evt_head - *start > (unsigned int)size)
evt_head -= pheader->size;
*end = evt_head;
return 0;
@@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
* Backward ring buffer is full. We still have a chance to read
* most of data from it.
*/
- if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
+ if (overwrite_rb_find_range(data, md->mask, startp, endp))
return -EINVAL;
}

--
1.7.12.4

2018-03-07 10:23:08

by Jiri Olsa

Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range

On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote:
> In overwrite mode, start will be set to head in perf_mmap__read_init.
> Therefore, it is no need to set the start one more in
> overwrite_rb_find_range and *start can be used as head instead of
> passing head to overwrite_rb_find_range.

it conflicts a little with recent cleanup from Kan Liang,,
https://marc.info/?t=152035082800001&r=1&w=2

otherwise it looks ok to me

jirka

>
> Signed-off-by: Yisheng Xie <[email protected]>
> ---
> tools/perf/util/mmap.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index 91531a7..6751ac9 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
> return 0;
> }
>
> -static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
> +static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
> {
> struct perf_event_header *pheader;
> - u64 evt_head = head;
> + u64 evt_head = *start;
> int size = mask + 1;
>
> - pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
> - pheader = (struct perf_event_header *)(buf + (head & mask));
> - *start = head;
> + pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
> + pheader = (struct perf_event_header *)(buf + (*start & mask));
> while (true) {
> - if (evt_head - head >= (unsigned int)size) {
> + if (evt_head - *start >= (unsigned int)size) {
> pr_debug("Finished reading overwrite ring buffer: rewind\n");
> - if (evt_head - head > (unsigned int)size)
> + if (evt_head - *start > (unsigned int)size)
> evt_head -= pheader->size;
> *end = evt_head;
> return 0;
> @@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
> * Backward ring buffer is full. We still have a chance to read
> * most of data from it.
> */
> - if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
> + if (overwrite_rb_find_range(data, md->mask, startp, endp))
> return -EINVAL;
> }
>
> --
> 1.7.12.4
>

2018-03-07 11:03:10

by Yisheng Xie

Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range

Hi jirka,

On 2018/3/7 18:21, Jiri Olsa wrote:
> On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote:
>> In overwrite mode, start will be set to head in perf_mmap__read_init.
>> Therefore, it is no need to set the start one more in
>> overwrite_rb_find_range and *start can be used as head instead of
>> passing head to overwrite_rb_find_range.
>
> it conflicts a little with recent cleanup from Kan Liang,,
> https://marc.info/?t=152035082800001&r=1&w=2
>
> otherwise it looks ok to me
>

I can send the next version based on Kan's patch after his patches are in the tree.

Thanks
Yisheng

> jirka
>
>>
>> Signed-off-by: Yisheng Xie <[email protected]>
>> ---
>> tools/perf/util/mmap.c | 15 +++++++--------
>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
>> index 91531a7..6751ac9 100644
>> --- a/tools/perf/util/mmap.c
>> +++ b/tools/perf/util/mmap.c
>> @@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
>> return 0;
>> }
>>
>> -static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
>> +static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
>> {
>> struct perf_event_header *pheader;
>> - u64 evt_head = head;
>> + u64 evt_head = *start;
>> int size = mask + 1;
>>
>> - pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
>> - pheader = (struct perf_event_header *)(buf + (head & mask));
>> - *start = head;
>> + pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
>> + pheader = (struct perf_event_header *)(buf + (*start & mask));
>> while (true) {
>> - if (evt_head - head >= (unsigned int)size) {
>> + if (evt_head - *start >= (unsigned int)size) {
>> pr_debug("Finished reading overwrite ring buffer: rewind\n");
>> - if (evt_head - head > (unsigned int)size)
>> + if (evt_head - *start > (unsigned int)size)
>> evt_head -= pheader->size;
>> *end = evt_head;
>> return 0;
>> @@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
>> * Backward ring buffer is full. We still have a chance to read
>> * most of data from it.
>> */
>> - if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
>> + if (overwrite_rb_find_range(data, md->mask, startp, endp))
>> return -EINVAL;
>> }
>>
>> --
>> 1.7.12.4
>>
>
> .
>

2018-03-07 14:00:11

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range

Em Wed, Mar 07, 2018 at 11:21:57AM +0100, Jiri Olsa escreveu:
> On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote:
> > In overwrite mode, start will be set to head in perf_mmap__read_init.
> > Therefore, it is no need to set the start one more in
> > overwrite_rb_find_range and *start can be used as head instead of
> > passing head to overwrite_rb_find_range.
>
> it conflicts a little with recent cleanup from Kan Liang,,
> https://marc.info/?t=152035082800001&r=1&w=2
>
> otherwise it looks ok to me

yeah, wait a while till I push Kan's simplifications and then resubmit,
ok?

- Arnaldo

> jirka
>
> >
> > Signed-off-by: Yisheng Xie <[email protected]>
> > ---
> > tools/perf/util/mmap.c | 15 +++++++--------
> > 1 file changed, 7 insertions(+), 8 deletions(-)
> >
> > diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> > index 91531a7..6751ac9 100644
> > --- a/tools/perf/util/mmap.c
> > +++ b/tools/perf/util/mmap.c
> > @@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
> > return 0;
> > }
> >
> > -static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
> > +static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
> > {
> > struct perf_event_header *pheader;
> > - u64 evt_head = head;
> > + u64 evt_head = *start;
> > int size = mask + 1;
> >
> > - pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
> > - pheader = (struct perf_event_header *)(buf + (head & mask));
> > - *start = head;
> > + pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
> > + pheader = (struct perf_event_header *)(buf + (*start & mask));
> > while (true) {
> > - if (evt_head - head >= (unsigned int)size) {
> > + if (evt_head - *start >= (unsigned int)size) {
> > pr_debug("Finished reading overwrite ring buffer: rewind\n");
> > - if (evt_head - head > (unsigned int)size)
> > + if (evt_head - *start > (unsigned int)size)
> > evt_head -= pheader->size;
> > *end = evt_head;
> > return 0;
> > @@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
> > * Backward ring buffer is full. We still have a chance to read
> > * most of data from it.
> > */
> > - if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
> > + if (overwrite_rb_find_range(data, md->mask, startp, endp))
> > return -EINVAL;
> > }
> >
> > --
> > 1.7.12.4
> >

2018-03-08 01:07:48

by Yisheng Xie

Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range

Hi Arnaldo,

On 2018/3/7 21:58, Arnaldo Carvalho de Melo wrote:
> Em Wed, Mar 07, 2018 at 11:21:57AM +0100, Jiri Olsa escreveu:
>> On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote:
>>> In overwrite mode, start will be set to head in perf_mmap__read_init.
>>> Therefore, it is no need to set the start one more in
>>> overwrite_rb_find_range and *start can be used as head instead of
>>> passing head to overwrite_rb_find_range.
>>
>> it conflicts a little with recent cleanup from Kan Liang,,
>> https://marc.info/?t=152035082800001&r=1&w=2
>>
>> otherwise it looks ok to me
>
> yeah, wait a while till I push Kan's simplifications and then resubmit,
> ok?
>
Sure, I will wait and resubmit.

Thanks
Yisheng

> - Arnaldo
>
>> jirka
>>
>>>
>>> Signed-off-by: Yisheng Xie <[email protected]>
>>> ---
>>> tools/perf/util/mmap.c | 15 +++++++--------
>>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
>>> index 91531a7..6751ac9 100644
>>> --- a/tools/perf/util/mmap.c
>>> +++ b/tools/perf/util/mmap.c
>>> @@ -223,19 +223,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
>>> return 0;
>>> }
>>>
>>> -static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
>>> +static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
>>> {
>>> struct perf_event_header *pheader;
>>> - u64 evt_head = head;
>>> + u64 evt_head = *start;
>>> int size = mask + 1;
>>>
>>> - pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
>>> - pheader = (struct perf_event_header *)(buf + (head & mask));
>>> - *start = head;
>>> + pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
>>> + pheader = (struct perf_event_header *)(buf + (*start & mask));
>>> while (true) {
>>> - if (evt_head - head >= (unsigned int)size) {
>>> + if (evt_head - *start >= (unsigned int)size) {
>>> pr_debug("Finished reading overwrite ring buffer: rewind\n");
>>> - if (evt_head - head > (unsigned int)size)
>>> + if (evt_head - *start > (unsigned int)size)
>>> evt_head -= pheader->size;
>>> *end = evt_head;
>>> return 0;
>>> @@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
>>> * Backward ring buffer is full. We still have a chance to read
>>> * most of data from it.
>>> */
>>> - if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
>>> + if (overwrite_rb_find_range(data, md->mask, startp, endp))
>>> return -EINVAL;
>>> }
>>>
>>> --
>>> 1.7.12.4
>>>
>
> .
>