LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Karsten Wiese <fzu@wemgehoertderstaat.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH -rt 0/3] Make trace_freerunning work; Take 2
Date: Wed, 6 Dec 2006 16:08:24 +0100	[thread overview]
Message-ID: <200612061608.24556.fzu@wemgehoertderstaat.de> (raw)
In-Reply-To: <20061205221046.GB20587@elte.hu>

Am Dienstag, 5. Dezember 2006 23:10 schrieb Ingo Molnar:
> 
> freerunning should behave the same way with regard to latency 
> measurement. I.e. report_latency() is still needed, and the kernel will 
> thus do a maximum search over all traces triggered via start/stop.
> 
> the difference is in the recording of the last-largest-latency:
> 
> - with !freerunning, the tracer stops recording after MAX_TRACE entries, 
>   i.e. the "head" of the trace is preserved in the trace buffer.
> 
> - with freerunning, the tracer never stops, it 'wraps around' after 
>   MAX_TRACE entries and starts overwriting the oldest entries. I.e. the  
>   "tail" of the trace is preserved in the trace buffer.
> 
> depending on the situation, freerunning or !freerunning might be the 
> more useful mode.
> 
> but there should be no difference in measurement.

Following 3 patches try to implement the above.

Tested on a UP only after this incantation:
	echo 0 > /proc/sys/kernel/wakeup_timing
	echo 1 > /proc/sys/kernel/trace_enabled
	echo 1 > /proc/sys/kernel/trace_user_triggered

and for half of tests:
	echo 1 > /proc/sys/kernel/trace_freerunning
or
	echo 0 > /proc/sys/kernel/trace_freerunning
.

      Karsten

  reply	other threads:[~2006-12-06 15:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20061205220257.1AECF3E2420@elvis.elte.hu>
2006-12-05 22:10 ` [PATCH -rt 2/3] Make trace_freerunning work Ingo Molnar
2006-12-06 15:08   ` Karsten Wiese [this message]
2006-12-06 15:12     ` [PATCH -rt 1/3] Make trace_freerunning work; Take 2: Off by 1 tweaks Karsten Wiese
2006-12-06 15:18       ` [PATCH -rt 2/3] Make trace_freerunning work; Take 2: Add atomic_t underrun Karsten Wiese
2006-12-06 15:26         ` [PATCH -rt 3/3] Make trace_freerunning work; Take 2: change reset_trace_idx() Karsten Wiese
2006-12-06 15:54     ` [PATCH -rt 0/3] Make trace_freerunning work; Take 2 Ingo Molnar

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=200612061608.24556.fzu@wemgehoertderstaat.de \
    --to=fzu@wemgehoertderstaat.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --subject='Re: [PATCH -rt 0/3] Make trace_freerunning work; Take 2' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).