From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754066AbeCGN7D (ORCPT ); Wed, 7 Mar 2018 08:59:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35980 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151AbeCGN7A (ORCPT ); Wed, 7 Mar 2018 08:59:00 -0500 Date: Wed, 7 Mar 2018 10:58:54 -0300 From: Arnaldo Carvalho de Melo To: Jiri Olsa Cc: Yisheng Xie , mingo@redhat.com, peterz@infradead.org, namhyung@kernel.org, acme@kernel.org, alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org, Kan Liang Subject: Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range Message-ID: <20180307135854.GA2187@redhat.com> References: <1520336663-53466-1-git-send-email-xieyisheng1@huawei.com> <20180307102157.GC22848@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180307102157.GC22848@krava> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > --- > > 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 > >