From: James Hogan <james.hogan@imgtec.com>
To: <linux-kernel@vger.kernel.org>
Cc: James Hogan <james.hogan@imgtec.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: [PATCH 2/9] metag: perf: fix wrap handling in delta calculation
Date: Fri, 15 Mar 2013 13:43:41 +0000 [thread overview]
Message-ID: <1363355028-23278-3-git-send-email-james.hogan@imgtec.com> (raw)
In-Reply-To: <1363355028-23278-1-git-send-email-james.hogan@imgtec.com>
When calculating the delta, mask with MAX_PERIOD (24 bits) to handle
wrapping, which particularly happens with periodic sampling since the
value is intentionally set so that it will overflow soon.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
---
arch/metag/kernel/perf/perf_event.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/metag/kernel/perf/perf_event.c b/arch/metag/kernel/perf/perf_event.c
index f38bf6d..8096db2 100644
--- a/arch/metag/kernel/perf/perf_event.c
+++ b/arch/metag/kernel/perf/perf_event.c
@@ -211,7 +211,7 @@ again:
/*
* Calculate the delta and add it to the counter.
*/
- delta = new_raw_count - prev_raw_count;
+ delta = (new_raw_count - prev_raw_count) & MAX_PERIOD;
local64_add(delta, &event->count);
}
--
1.8.1.2
next prev parent reply other threads:[~2013-03-15 13:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-15 13:43 [PATCH 0/9] metag: perf fixes and OProfile support James Hogan
2013-03-15 13:43 ` [PATCH 1/9] metag: perf: fix core internal / perf channel mux James Hogan
2013-03-15 13:43 ` James Hogan [this message]
2013-03-15 13:43 ` [PATCH 3/9] metag: perf: fixes for interrupting perf counters James Hogan
2013-03-15 13:43 ` [PATCH 4/9] metag: perf: add missing prev_count updates James Hogan
2013-03-15 13:43 ` [PATCH 5/9] metag: perf: fix frequency sampling (dynamic period) James Hogan
2013-03-15 13:43 ` [PATCH 6/9] metag: perf: use hard_processor_id() to get thread James Hogan
2013-03-15 13:43 ` [PATCH 7/9] metag: perf: don't reset TXTACTCYC James Hogan
2013-03-15 13:43 ` [PATCH 8/9] metag: perf: prepare for use by oprofile James Hogan
2013-03-15 13:43 ` [PATCH 9/9] metag: OProfile support James Hogan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1363355028-23278-3-git-send-email-james.hogan@imgtec.com \
--to=james.hogan@imgtec.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@ghostprotocols.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=paulus@samba.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®