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Re: Why systemtap loses events and what can be done about it?
Hi -
On Tue, Sep 04, 2007 at 11:53:58AM -0700, Brad Peters wrote:
> [...] Definitely an interesting idea; Given Frank's concern, it
> seems that all data collection would have to take place in the
> front-end handler.
Yeah, but that cancels one of the possible advantages of deferred
handling: the ability to sleep within probe handlers. Some data
requires sleeping to extract "reliably" (in terms of data correctness;
unfortunately this tends to introduce deadlocks, so we don't do it).
> The Bluedye team (Mike Strosaker, Nathan Fontenot and myself)
> implemented something similar, collecting data immediately after a
> probe is hit, then using a work queue to do all relay channel writes
> at a later time (i.e., when interrupts are enabled).
(A quick google search can't find any public info about BlueDye.)
> I have no idea what time-savings we saw, but I will find some time
> today to hack out our work-queue code and look at the timing impact
Thanks, should be interesting.
- FChE