Messages in this thread | | | Date | Mon, 17 Mar 2008 06:21:34 +0100 | From | Willy Tarreau <> | Subject | Re: Poor PostgreSQL scaling on Linux 2.6.25-rc5 (vs 2.6.22) |
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On Sun, Mar 16, 2008 at 10:16:36PM -0700, Ray Lee wrote: > On Sun, Mar 16, 2008 at 5:44 PM, Nick Piggin <nickpiggin@yahoo.com.au> wrote: > > I don't see how it is really helpful for interactive processes either. > > By definition, if they are not CPU bound, then they should be run > > quite soon after waking up; if they are CPU bound, then reducing > > efficiency by increasing context switches is effectively going to > > increase their latency anyway. > > How? Are you saying that switching the granularity to, say, 25ms, will > *decrease* the latency of interactive tasks? > > And the efficiency we're talking about reducing here is due to the > fact that tasks are hitting cold caches more times per second when the > granularity is smaller, correct? Or are you concerned by another > issue? > > > Can this be changed by default, please? > > Not without benchmarks of interactivity, please. There are far, far > more linux desktops than there are servers. People expect to have to > tune servers (I do, for the servers I maintain). People don't expect > to have to tune a desktop to make it run well.
Oh and even on servers, when your anti-virus proxy reaches a load of 800, you're happy no to have too large a time-slice so that you regularly get a chance of being allowed to type in commands over SSH.
Large time-slices are needed only in HPC environments IMHO, where only one task runs.
Willy
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