From: Oleg Nesterov <oleg@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Namhyung Kim <namhyung.kim@lge.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Hyeoncheol Lee <cheol.lee@lge.com>,
Hemant Kumar <hkshaw@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
"zhangwei(Jovi)" <jovi.zhangwei@huawei.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: Re: [PATCH 10/13] tracing/uprobes: Fetch args before reserving a ring buffer
Date: Fri, 1 Nov 2013 16:09:10 +0100 [thread overview]
Message-ID: <20131101150910.GA18278@redhat.com> (raw)
In-Reply-To: <1383029621-7384-11-git-send-email-namhyung@kernel.org>
Hi Namhyung,
Sorry if this was already discussed. But I can't really understand
the idea of this per-cpu buffer...
On 10/29, Namhyung Kim wrote:
>
> Fetching from user space should be done in a non-atomic context. So
> use a per-cpu buffer and copy its content to the ring buffer
> atomically. Note that we can migrate during accessing user memory
> thus use a per-cpu mutex to protect concurrent accesses.
And if the task migrates or just sleeps in page fault, another task
which hits another uprobe on the same CPU should wait.
Why we can't simply add trace_uprobe->buffer instead? Only to save
some memory? But every uprobe is very expensive in this sense anyway.
Oleg.
next prev parent reply other threads:[~2013-11-01 15:09 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-29 6:53 [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6) Namhyung Kim
2013-10-29 6:53 ` [PATCH 01/13] tracing/uprobes: Fix documentation of uprobe registration syntax Namhyung Kim
2013-10-29 6:53 ` [PATCH 02/13] tracing/probes: Fix basic print type functions Namhyung Kim
2013-10-29 6:53 ` [PATCH 03/13] tracing/kprobes: Move fetch functions to trace_kprobe.c Namhyung Kim
2013-10-29 6:53 ` [PATCH 04/13] tracing/kprobes: Add fetch{,_size} member into deref fetch method Namhyung Kim
2013-10-29 6:53 ` [PATCH 05/13] tracing/kprobes: Staticize stack and memory fetch functions Namhyung Kim
2013-10-29 6:53 ` [PATCH 06/13] tracing/kprobes: Factor out struct trace_probe Namhyung Kim
2013-10-29 6:53 ` [PATCH 07/13] tracing/uprobes: Convert to " Namhyung Kim
2013-10-29 6:53 ` [PATCH 08/13] tracing/kprobes: Move common functions to trace_probe.h Namhyung Kim
2013-10-29 6:53 ` [PATCH 09/13] tracing/kprobes: Integrate duplicate set_print_fmt() Namhyung Kim
2013-10-29 6:53 ` [PATCH 10/13] tracing/uprobes: Fetch args before reserving a ring buffer Namhyung Kim
2013-10-31 18:16 ` Oleg Nesterov
2013-11-01 9:00 ` Namhyung Kim
2013-11-04 8:06 ` Namhyung Kim
2013-11-04 14:35 ` Oleg Nesterov
2013-11-05 1:12 ` Namhyung Kim
2013-11-01 15:09 ` Oleg Nesterov [this message]
2013-11-01 15:22 ` Oleg Nesterov
2013-11-03 20:20 ` Oleg Nesterov
2013-11-04 8:11 ` Namhyung Kim
2013-11-04 14:38 ` Oleg Nesterov
2013-11-05 1:17 ` Namhyung Kim
2013-10-29 6:53 ` [PATCH 11/13] tracing/kprobes: Add priv argument to fetch functions Namhyung Kim
2013-11-04 16:09 ` Oleg Nesterov
2013-11-05 2:10 ` Namhyung Kim
2013-10-29 6:53 ` [PATCH 12/13] tracing/uprobes: Add more " Namhyung Kim
2013-10-31 18:22 ` Oleg Nesterov
2013-11-04 8:50 ` Namhyung Kim
2013-11-04 16:44 ` Oleg Nesterov
2013-11-04 17:17 ` Steven Rostedt
2013-11-05 2:19 ` Namhyung Kim
2013-11-05 2:17 ` Namhyung Kim
2013-11-01 17:53 ` Oleg Nesterov
2013-10-29 6:53 ` [PATCH 13/13] tracing/uprobes: Add support for full argument access methods Namhyung Kim
2013-10-30 10:36 ` [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6) Masami Hiramatsu
2013-11-02 15:54 ` Oleg Nesterov
2013-11-04 8:46 ` Namhyung Kim
2013-11-04 8:59 ` Namhyung Kim
2013-11-04 15:51 ` Oleg Nesterov
2013-11-04 16:22 ` Oleg Nesterov
2013-11-04 18:47 ` Oleg Nesterov
2013-11-04 18:57 ` Oleg Nesterov
2013-11-05 2:51 ` Namhyung Kim
2013-11-05 16:41 ` Oleg Nesterov
2013-11-06 8:37 ` Namhyung Kim
2013-11-05 2:49 ` Namhyung Kim
2013-11-05 6:58 ` Namhyung Kim
2013-11-05 17:45 ` Oleg Nesterov
2013-11-05 19:24 ` Oleg Nesterov
2013-11-06 8:57 ` Namhyung Kim
2013-11-06 17:37 ` Oleg Nesterov
2013-11-06 18:24 ` Oleg Nesterov
2013-11-07 9:00 ` Namhyung Kim
2013-11-08 17:00 ` Oleg Nesterov
2013-11-12 7:49 ` Namhyung Kim
2013-11-07 8:48 ` Namhyung Kim
2013-11-09 3:18 ` Masami Hiramatsu
2013-11-09 15:23 ` Oleg Nesterov
2013-11-12 8:00 ` Namhyung Kim
2013-11-12 18:44 ` Oleg Nesterov
2013-11-25 6:59 ` Namhyung Kim
2013-11-25 14:12 ` [PATCH] uprobes: Allocate ->utask before handler_chain() for tracing handlers Oleg Nesterov
2013-11-06 8:48 ` [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6) Namhyung Kim
2013-11-06 16:28 ` Oleg Nesterov
2013-11-07 7:33 ` Namhyung Kim
2013-11-08 16:52 ` Oleg Nesterov
2013-11-05 2:15 ` Namhyung Kim
2013-11-05 16:33 ` Oleg Nesterov
2013-11-06 8:34 ` Namhyung Kim
2013-11-05 1:59 ` Namhyung Kim
2013-11-04 15:01 ` Oleg Nesterov
2013-11-05 1:53 ` Namhyung Kim
2013-11-05 16:28 ` Oleg Nesterov
2013-11-06 8:31 ` Namhyung Kim
-- strict thread matches above, loose matches on Subject: below --
2013-09-03 5:44 [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v5) Namhyung Kim
2013-09-03 5:44 ` [PATCH 10/13] tracing/uprobes: Fetch args before reserving a ring buffer Namhyung Kim
2013-09-03 10:50 ` Masami Hiramatsu
2013-09-04 7:08 ` Namhyung Kim
2013-09-03 11:10 ` zhangwei(Jovi)
2013-09-04 7:10 ` Namhyung Kim
2013-08-27 8:48 [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v4) Namhyung Kim
2013-08-27 8:48 ` [PATCH 10/13] tracing/uprobes: Fetch args before reserving a ring buffer Namhyung Kim
2013-08-09 8:44 [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v3) Namhyung Kim
2013-08-09 8:45 ` [PATCH 10/13] tracing/uprobes: Fetch args before reserving a ring buffer Namhyung Kim
2013-08-09 9:56 ` Masami Hiramatsu
2013-08-09 16:20 ` Oleg Nesterov
2013-08-09 16:21 ` Oleg Nesterov
2013-08-10 1:26 ` zhangwei(Jovi)
2013-08-10 1:41 ` zhangwei(Jovi)
2013-08-10 14:06 ` zhangwei(Jovi)
2013-08-22 16:42 ` Steven Rostedt
2013-08-22 23:57 ` zhangwei(Jovi)
2013-08-23 1:08 ` Steven Rostedt
2013-08-27 8:07 ` Namhyung Kim
2013-08-23 4:22 ` Masami Hiramatsu
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