From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCHv4] perf x86_64: Fix rsp register for system call fast path
Date: Wed, 03 Oct 2012 15:22:17 +0200 [thread overview]
Message-ID: <1349270537.7780.47.camel@twins> (raw)
In-Reply-To: <20121003131344.GC945@krava.brq.redhat.com>
On Wed, 2012-10-03 at 15:13 +0200, Jiri Olsa wrote:
> @@ -1190,8 +1191,8 @@ static inline void perf_sample_data_init(struct
> perf_sample_data *data,
> data->raw = NULL;
> data->br_stack = NULL;
> data->period = period;
> - data->regs_user.abi = PERF_SAMPLE_REGS_ABI_NONE;
> - data->regs_user.regs = NULL;
> + /* Sets abi to PERF_SAMPLE_REGS_ABI_NONE. */
> + memset(&data->regs_user, 0, sizeof(data->regs_user));
> data->stack_user_size = 0;
> }
Hmm, this will slow down all events, regardless of whether they use any
of that stuff or not. Since the one user actually does something like:
data->regs_user = *pt_regs;
except it does a memcpy() for some obscure reason, it really doesn't
matter what is in there when uninitialized, right?
next prev parent reply other threads:[~2012-10-03 13:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-01 17:31 [PATCH] perf x86_64: Fix rsp register for system call fast path Jiri Olsa
2012-10-02 10:44 ` Peter Zijlstra
2012-10-02 14:58 ` [PATCHv2] " Jiri Olsa
2012-10-02 15:49 ` Frederic Weisbecker
2012-10-02 16:06 ` Jiri Olsa
2012-10-02 16:16 ` Frederic Weisbecker
2012-10-03 12:29 ` [PATCHv3] " Jiri Olsa
2012-10-03 12:35 ` Frederic Weisbecker
2012-10-03 13:13 ` [PATCHv4] " Jiri Olsa
2012-10-03 13:22 ` Peter Zijlstra [this message]
2012-10-03 13:30 ` Jiri Olsa
2012-10-04 10:38 ` [PATH 0/2] perf: x86_64 rsp related changes Jiri Olsa
2012-10-04 10:38 ` [PATCH 1/2] perf x86_64: Fix rsp register for system call fast path Jiri Olsa
2012-10-04 10:38 ` [PATCH 2/2] perf: Simplify the sample's user regs/stack retrieval Jiri Olsa
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