From: Yisheng Xie <xieyisheng1@huawei.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: <acme@redhat.com>, <mingo@redhat.com>, <peterz@infradead.org>,
<namhyung@kernel.org>, <alexander.shishkin@linux.intel.com>,
<linux-kernel@vger.kernel.org>,
Kan Liang <kan.liang@linux.intel.com>
Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range
Date: Wed, 7 Mar 2018 19:01:40 +0800 [thread overview]
Message-ID: <2c7d1fe9-aeca-653e-569d-3078375bf588@huawei.com> (raw)
In-Reply-To: <20180307102157.GC22848@krava>
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 <xieyisheng1@huawei.com>
>> ---
>> 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
>>
>
> .
>
next prev parent reply other threads:[~2018-03-07 11:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-06 11:44 [PATCH] perf mmap: Discard head in overwrite_rb_find_range Yisheng Xie
2018-03-07 10:21 ` Jiri Olsa
2018-03-07 11:01 ` Yisheng Xie [this message]
2018-03-07 13:58 ` Arnaldo Carvalho de Melo
2018-03-08 1:05 ` Yisheng Xie
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