From: "Stone, Joshua I" <joshua.i.stone@intel.com>
To: <maynardj@us.ibm.com>, "William Cohen" <wcohen@redhat.com>
Cc: "SystemTAP" <systemtap@sources.redhat.com>
Subject: RE: Proposed systemtap access to perfmon hardware
Date: Wed, 22 Mar 2006 23:46:00 -0000 [thread overview]
Message-ID: <CBDB88BFD06F7F408399DBCF8776B3DC06BC0DD0@scsmsx403.amr.corp.intel.com> (raw)
Maynard Johnson wrote:
> William Cohen wrote:
>> The individual start and stop operations would be allowed.
> This is not so good. Besides the fact that it may be difficult (or
> impossible) to do, I don't see it being all that useful. But then,
> I'm a tool developer, not a performance analyst, so I could be
> missing the point.
Enabling start & stop lets you narrow the context that you want to
measure. Perfmon can only give you thread level virtualization of the
counters. With start & stop I can, for example, start the counters when
I enter sys_open and stop when I return. Now if I want I can get a
microbenchmark of IPC for the sys_open call (and its callees).
But this also opens up possibilities for more obscure "contexts" -
perhaps I want to start counting when a network packet is received and
stop when it is delivered to the thread. Any probepoint you can do
today can become a start/stop point for the counters.
Josh
next reply other threads:[~2006-03-22 23:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-22 23:46 Stone, Joshua I [this message]
2006-03-23 12:54 ` Maynard Johnson
2006-03-23 14:46 ` William Cohen
-- strict thread matches above, loose matches on Subject: below --
2006-03-23 17:09 Stone, Joshua I
2006-03-22 23:23 Stone, Joshua I
2006-03-22 19:09 Stone, Joshua I
2006-03-22 20:04 ` Frank Ch. Eigler
2006-03-15 16:24 William Cohen
2006-03-15 22:34 ` Frank Ch. Eigler
2006-03-17 16:20 ` William Cohen
2006-03-17 17:10 ` Bill Rugolsky Jr.
2006-03-17 17:34 ` Frank Ch. Eigler
2006-03-17 20:26 ` William Cohen
2006-03-20 17:27 ` Frank Ch. Eigler
2006-03-22 3:34 ` Maynard Johnson
2006-03-22 18:02 ` William Cohen
2006-03-22 22:16 ` Maynard Johnson
2006-03-22 18:30 ` Frank Ch. Eigler
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