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PR 6504
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: systemtap at sources dot redhat dot com
- Date: Fri, 16 May 2008 07:23:33 -0400
- Subject: PR 6504
- References: <482C8404.6080308@redhat.com> <mailman.4430.1210880070.3267.external-perftools-list@redhat.com>
Masami Hiramatsu <mhiramat@redhat.com> writes:
> [...] Actually, relay_switch_subbuf() doesn't call any kernel
> functions except __mod_timer (others are primitive inlines or
> macros). so, with current patch which is for systemtap runtime, you
> don't need to update the blacklist.
That's good. The patch attached to bug #6504 looks plausible - I'm
not a utt/runtime expert - but I'm worried by a few things. It seems
like there are several possible races (utt->wakeup being set/cleared;
_utt_wakeup_readers:waitqueue_active vs. wake_up_interruptible), and
the UTT_TIMER_INTERVAL seems too small as an unconditional poll. (I
wonder the same thing about STP_WORK_TIMER in
runtime/transport/transport.c.)
To what extent could a delayed-work backend simplify this code? (If
that subsystem needs to be blacklisted, so be it.)
- FChE