From: fche@redhat.com (Frank Ch. Eigler)
To: systemtap@sourceware.org
Subject: Re: static user probe performance
Date: Wed, 07 Apr 2010 14:43:00 -0000 [thread overview]
Message-ID: <y0mljczfhmn.fsf@fche.csb> (raw)
In-Reply-To: <y0mvdc6exho.fsf@fche.csb> (Frank Ch. Eigler's message of "Mon, 05 Apr 2010 11:21:23 -0400")
>> run with stap
>> [...]
>> elapsed time
>> volatile semaphore 1858.71
>> no volatile no semaphore 1865.68
>> volatile no semaphore 1873.07
>> no volatile semaphore 1878.09
>
> So for this particular microbenchmark, systemtap probing imposes a 30x
> slowdown, yikes. How many probe hits does this represent?
From scox's later numbers, that's 192 million hits, for about 9
us/hit, which seems rather high. (In this microbenchmark, it seems
that the instrumentation is taking an impressive 98% of the cpu time,
which ought to have triggered the overload protection. I assume there
was an -DSTP_NO_OVERLOAD in effect.)
- FChE
next prev parent reply other threads:[~2010-04-07 14:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-25 18:34 Stan Cox
2010-04-02 20:53 ` Stan Cox
2010-04-05 15:21 ` Frank Ch. Eigler
2010-04-07 14:26 ` Stan Cox
2010-04-07 14:43 ` Frank Ch. Eigler [this message]
2010-04-07 18:10 ` Josh Stone
2010-04-07 19:10 ` Jim Keniston
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