On Thursday 01 September 2005 14:18, Con Kolivas wrote: > On Fri, 2 Sep 2005 00:18, Hans Kristian Rosbach wrote: > > On Thu, 2005-09-01 at 23:46 +1000, Con Kolivas wrote: > > > Here is a working swap prefetching patch for 2.6.13. I have > > > resuscitated and rewritten some early prefetch code Thomas Schlichter > > > did in late 2.5 to create a configurable kernel thread that reads in > > > swap from ram in reverse order it was written out. It does this once > > > kswapd has been idle for a minute (implying no current vm stress). This > > > patch attached below is a rollup of two patches the current versions of > > > which are here:
> > That said, I have often thought it might be good to have something like > > pre-writing swap, ie reverse what your patch does. > > > > In other words it'd keep as much of swappable data on disk as possible, > > but without removing it from memory. So when it comes time to free up > > some memory, the data is already on disk so no performance penalty from > > writing it out. both ideas make all the sense to me. I'll give it a try, but in what way can we test this kind of enhancement? maybe write a small program that starts fills a good part of swap space and then, after 1min idle, 'watch free -m' should show free memory decreasing (not counting cache/buffers) with idle activity. decent? about the Hans's proposal - it would increase power consumption, because of increased disk activity. about con's swap prefetch, I'm not so sure... regards, pedro venda. -- Pedro João Lopes Venda email: pjvenda < at > arrakis.dhis.org http://arrakis.dhis.org
pgpzSMFT9Chwo.pgp
Description: PGP signature
