[linux-mm-cc] Announce: ccache release 0.1
nitingupta910 at gmail.com
Fri Feb 22 03:38:30 EST 2008
On Fri, Feb 22, 2008 at 1:56 PM, John McCabe-Dansted <gmatht at gmail.com> wrote:
> On Tue, Feb 19, 2008 at 11:04 PM, Nitin Gupta <nitingupta910 at gmail.com> wrote:
> > > > > BTW, why is the default 10% of mem?
> > >
> > > Perhaps 100% (or maybe 50%) would be a more sensible default? For me
> > > 66% makes a huge difference to the Hardy liveCD performance. 10% makes
> > > a difference but 50%+ goes from "ls /" taking 10s to snappy
> > > performance even on large applications like Firefox.
> > >
> > I think this depends a lot on kind of workload and system. For e.g:
> > - On desktops, retaining too many anonymous pages at cost of
> > continuously losing page-cache (filesystem-backed) pages can hurt
> > performance for workload that repeatedly access same file(s).
> > - On embedded systems, too much de/compression will drain all battery.
> > and so on...
> I was thinking that for the LiveCD case the primary performance hit
> would be seeking on the CD drive. Hence to maximize memory available
> for caching the CD, we should
> 1) Use 100% mem for compcache.
> 2) Set compcaches priority to be low, so that hdd swap will be used
> first if it exists.
> Does this seem reasonable?
Setting compcache prio < hdd swap will not be good. After all,
compcache can potentially avoid swapping to slow hard-disks improving
system performance significantly. If compcache is not sufficient to
store all pages then only we should let it go to lower prio swaps.
> > Unfortunately none of these messages suggest why crash happened.
> > If you can send entire log, that will probably be more useful.
> I now tested this with QEMU and -smp 2. Still cannot reproduce the
> bug. QEMU doesn't seem to use both host CPUs so I presume it doesn't
> interleave instructions nearly as much as real SMP would.
> I'll test this some more on my real hardware (crosses fingers)
> John C. McCabe-Dansted
> PhD Student
> University of Western Australia
Thanks a lot for your testing efforts.
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