From: Peter Zijlstra <peterz@infradead.org>
To: rostedt@goodmis.org
Cc: Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 09/10] perf: Remove more fastpath code
Date: Fri, 21 May 2010 13:18:06 +0200 [thread overview]
Message-ID: <1274440686.1674.1705.camel@laptop> (raw)
In-Reply-To: <1274440538.26328.3575.camel@gandalf.stny.rr.com>
On Fri, 2010-05-21 at 07:15 -0400, Steven Rostedt wrote:
> > - if (WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0))
> > - return;
>
> Are you sure you want to remove this? I mean, sanity checks are a small
> cost (I have several in the ftrace ring buffer) and can catch bugs in
> case something happens during development. Especially when the code is
> under a lot of flux.
Yeah, I pondered adding a CONFIG_PERF_DEBUG for that.. thing is I was
tracking 2 variables just for this, and that seemed a bit excessive.
> I even have a sanity check that Ingo asked me to add, which would detect
> if a tracer (not the ring buffer, but the user of the ring buffer)
> recursed on itself. I think that check detected one bug in the function
> tracer in the begging, but hasn't caught anything since.
I still have recursion checks.
next prev parent reply other threads:[~2010-05-21 11:18 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-21 9:02 [PATCH 00/10] perf tracepoint and output optimizations Peter Zijlstra
2010-05-21 9:02 ` [PATCH 01/10] perf, trace: Remove IRQ-disable from perf/tracepoint interaction Peter Zijlstra
2010-05-21 17:43 ` Frank Ch. Eigler
2010-05-21 17:53 ` Steven Rostedt
2010-05-21 18:07 ` Frank Ch. Eigler
2010-05-23 12:11 ` Paul Mackerras
2010-05-23 18:16 ` Peter Zijlstra
2010-05-24 4:29 ` Paul Mackerras
2010-05-25 8:06 ` [tip:perf/core] perf, trace: Fix IRQ-disable removal " tip-bot for Peter Zijlstra
2010-05-25 9:02 ` Peter Zijlstra
2010-05-25 9:30 ` [tip:perf/core] perf, trace: Fix !x86 build bug tip-bot for Peter Zijlstra
2010-05-24 11:31 ` [PATCH 01/10] perf, trace: Remove IRQ-disable from perf/tracepoint interaction Frederic Weisbecker
2010-05-25 7:30 ` [PATCH 01a/10] perf, trace: Fix !x86 build issue Peter Zijlstra
2010-05-21 9:02 ` [PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to track events Peter Zijlstra
2010-05-21 9:40 ` Frederic Weisbecker
2010-05-21 10:02 ` Peter Zijlstra
2010-05-21 10:13 ` Frederic Weisbecker
2010-05-21 10:15 ` Peter Zijlstra
2010-05-21 10:19 ` Frederic Weisbecker
2010-05-21 10:38 ` Ingo Molnar
2010-05-21 10:51 ` Ingo Molnar
2010-05-21 10:19 ` Peter Zijlstra
2010-05-21 10:21 ` Frederic Weisbecker
2010-05-21 10:34 ` Peter Zijlstra
2010-05-21 10:38 ` Frederic Weisbecker
2010-05-21 10:41 ` [PATCH 02b/10] perf, trace: Fix probe unregister race Peter Zijlstra
2010-05-21 10:43 ` Frederic Weisbecker
2010-05-31 7:19 ` [tip:perf/urgent] perf_events, " tip-bot for Peter Zijlstra
2010-05-21 11:28 ` [tip:perf/core] perf, trace: Optimize tracepoints by using per-tracepoint-per-cpu hlist to track events tip-bot for Peter Zijlstra
2010-05-21 14:04 ` [PATCH 02/10] perf, trace: Use " Steven Rostedt
2010-05-21 14:18 ` Peter Zijlstra
2010-05-21 14:25 ` Peter Zijlstra
2010-05-31 7:20 ` [tip:perf/urgent] perf_events, trace: Fix perf_trace_destroy(), mutex went missing tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 03/10] perf: Ensure IOC_OUTPUT isnt used to create multi-writer buffers Peter Zijlstra
2010-05-21 11:28 ` [tip:perf/core] perf: Ensure that IOC_OUTPUT isn't " tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 04/10] perf-record: Remove -M Peter Zijlstra
2010-05-21 11:28 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 05/10] perf-record: Share per-cpu buffers Peter Zijlstra
2010-05-21 9:44 ` Frederic Weisbecker
2010-05-21 10:03 ` Peter Zijlstra
2010-05-21 11:29 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 06/10] perf: Fix wakeup storm for RO mmap()s Peter Zijlstra
2010-05-21 11:29 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 07/10] perf: Optimize perf_output_copy Peter Zijlstra
2010-05-21 11:29 ` [tip:perf/core] perf: Optimize perf_output_copy() tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 08/10] perf: Optimize the !vmalloc backed buffer Peter Zijlstra
2010-05-21 11:29 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 09/10] perf: Remove more fastpath code Peter Zijlstra
2010-05-21 11:15 ` Steven Rostedt
2010-05-21 11:18 ` Peter Zijlstra [this message]
2010-05-21 11:30 ` [tip:perf/core] perf: Remove more code from the fastpath tip-bot for Peter Zijlstra
2010-05-21 9:02 ` [PATCH 10/10] perf: Optimize perf_tp_event_match Peter Zijlstra
2010-05-21 11:30 ` [tip:perf/core] perf: Optimize perf_tp_event_match() tip-bot for Peter Zijlstra
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