mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: "Jin, Yao" <yao.jin@linux.intel.com>
Cc: Kyle Huey <me@kylehuey.com>, Mark Rutland <mark.rutland@arm.com>,
	gregkh@linuxfoundation.org, Peter Zijlstra <peterz@infradead.org>,
	Vince Weaver <vincent.weaver@maine.edu>,
	stable@vger.kernel.org,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Jiri Olsa <jolsa@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Stephane Eranian <eranian@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	acme@kernel.org, jolsa@kernel.org, kan.liang@intel.com,
	Will Deacon <will.deacon@arm.com>,
	open list <linux-kernel@vger.kernel.org>,
	"Robert O'Callahan" <robert@ocallahan.org>
Subject: Re: [PATCH] perf/core: generate overflow signal when samples are dropped (WAS: Re: [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region)
Date: Wed, 12 Jul 2017 09:57:11 +0200	[thread overview]
Message-ID: <20170712075711.vojapr64cq75dqen@gmail.com> (raw)
In-Reply-To: <b0610f44-09df-c36d-9d91-310b84c40c77@linux.intel.com>


* Jin, Yao <yao.jin@linux.intel.com> wrote:

> Could we provide 2 options in user space when enabling the event sampling?
> 
> One option is for the use case like rr debugger which only cares the PMI 
> interrupt but doesn't care the skid. The skid samples doesn't need to be 
> dropped.

Since it's an information leak, this is not something we want to expose as an 
interface. It's also a very ugly interface: why not just *clear* the sample, 
instead of dropping it?

The hardware messed up and gave us something we specifically did not permit 
user-space to collect. We have to fix the bad effects to the best extent we can, 
and not based on some knob.

Thanks,

	Ingo

  reply	other threads:[~2017-07-12  7:57 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAP045Ap8cMx6mzSgcQ3n3bnh_8GJuCp7_KZe_5ZTCR_K6cPTLw@mail.gmail.com>
2017-06-28  1:01 ` [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region Kyle Huey
2017-06-28  2:09   ` Jin, Yao
2017-06-28  4:51     ` Kyle Huey
2017-06-28  5:35       ` Jin, Yao
2017-06-28  7:30         ` Kyle Huey
2017-06-28 10:12       ` Mark Rutland
2017-06-28 10:56         ` [PATCH] perf/core: generate overflow signal when samples are dropped (WAS: Re: [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region) Mark Rutland
2017-06-28 12:40           ` Vince Weaver
2017-06-28 13:07             ` Mark Rutland
2017-06-29  8:13               ` Alexey Budankov
2017-06-29  8:25                 ` Alexey Budankov
2017-06-28 16:48           ` Kyle Huey
2017-06-28 17:49             ` Mark Rutland
2017-06-28 22:55               ` Kyle Huey
2017-06-29  0:27                 ` Jin, Yao
2017-06-30 17:44                 ` Kyle Huey
2017-07-04  9:03                 ` Peter Zijlstra
2017-07-04  9:33                   ` Mark Rutland
2017-07-04  9:46                     ` Peter Zijlstra
2017-07-04 10:21                     ` Mark Rutland
2017-07-06  5:07                       ` Robert O'Callahan
2017-07-11  2:03                         ` Kyle Huey
2017-07-11  9:03                           ` Ingo Molnar
2017-07-11 13:07                             ` Jin, Yao
2017-07-12  7:57                               ` Ingo Molnar [this message]
2017-07-11 14:26                             ` Mark Rutland
2017-07-11 15:32                             ` Kyle Huey
2017-07-18  0:07                               ` Kyle Huey
2017-06-29  8:12               ` Ingo Molnar
2017-07-04  9:06                 ` Peter Zijlstra
2017-07-04 10:04                   ` Ingo Molnar
2017-07-11  9:03           ` [tip:perf/urgent] Revert "perf/core: Drop kernel samples even though :u is specified" tip-bot for Ingo Molnar
2017-06-28 16:46         ` [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region Kyle Huey
2017-06-28 17:19           ` Mark Rutland
2017-06-28 17:36             ` Kyle Huey
2017-06-28 17:52               ` Mark Rutland
2017-06-28 17:48             ` Robert O'Callahan

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=20170712075711.vojapr64cq75dqen@gmail.com \
    --to=mingo@kernel.org \
    --cc=acme@kernel.org \
    --cc=acme@redhat.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=eranian@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jolsa@kernel.org \
    --cc=jolsa@redhat.com \
    --cc=kan.liang@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=me@kylehuey.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=robert@ocallahan.org \
    --cc=stable@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=vincent.weaver@maine.edu \
    --cc=will.deacon@arm.com \
    --cc=yao.jin@linux.intel.com \
    /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
Powered by JetHome