public inbox for systemtap@sourceware.org
 help / color / mirror / Atom feed
From: "fche at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sources.redhat.com
Subject: [Bug runtime/5194] IO problem on begin/end probes
Date: Thu, 18 Oct 2007 15:19:00 -0000	[thread overview]
Message-ID: <20071018151900.31080.qmail@sourceware.org> (raw)
In-Reply-To: <20071018140048.5194.hunt@redhat.com>


------- Additional Comments From fche at redhat dot com  2007-10-18 15:18 -------
(In reply to comment #3)
> calling a sleeping function in a begin probe.

That remains invalid, even with the slight relaxing we did earlier.

> If the begin/end probe does sleep or get interrupted, it might
> not get the same cpu when it resumes,

Interrupts do not cause a reschedule or cpu reassingnment if
preemption was blocked (as it is).

> which means the output buffer will change without the
> previous buffer getting flushed and data will be lost.

If this is the limit of what can happen when a user schemes to call
a sleeping function (which can only happen in "-g" mode anyway), then
this problem is a minor one.

> IIRC, one of the reasons we enabled preemption was to handle situations where
> large arrays are dumped during end probes.

That was only a side-effect.  We wanted to produce "long" reports, for "long"
meaning perhaps thousands of lines.  It's not megabytes.  With the status
quo, SMP machines may be able to keep up with even that.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=5194

------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

  parent reply	other threads:[~2007-10-18 15:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-18 14:01 [Bug runtime/5194] New: " hunt at redhat dot com
2007-10-18 14:10 ` [Bug runtime/5194] " fche at redhat dot com
2007-10-18 14:11 ` fche at redhat dot com
2007-10-18 14:25 ` hunt at redhat dot com
2007-10-18 15:19 ` fche at redhat dot com [this message]
2008-01-21 17:42 ` fche at redhat dot com
2008-01-21 17:56 ` hunt at redhat dot com
2008-01-21 18:13 ` [Bug runtime/5194] IO problem on begin/end probes; need fche at redhat dot com
2008-01-21 18:37 ` fche at redhat dot com
2008-01-29 16:40 ` fche at redhat dot com
2008-01-29 17:08 ` hunt at redhat dot com

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=20071018151900.31080.qmail@sourceware.org \
    --to=sourceware-bugzilla@sourceware.org \
    --cc=systemtap@sources.redhat.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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).