From: Peter Zijlstra Date: Wed, 14 Jan 2009 11:39:19 +0000 (+0100) Subject: sched: prefer wakers X-Git-Tag: v2.6.30-rc1~658^2~26 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e52fb7c097238d34f4d8e2a596f8a3f85b0c0565;p=pandora-kernel.git sched: prefer wakers Prefer tasks that wake other tasks to preempt quickly. This improves performance because more work is available sooner. The workload that prompted this patch was a kernel build over NFS4 (for some curious and not understood reason we had to revert commit: 18de9735300756e3ca9c361ef58409d8561dfe0d to make any progress at all) Without this patch a make -j8 bzImage (of x86-64 defconfig) would take 3m30-ish, with this patch we're down to 2m50-ish. psql-sysbench/mysql-sysbench show a slight improvement in peak performance as well, tbench and vmark seemed to not care. It is possible to improve upon the build time (to 2m20-ish) but that seriously destroys other benchmarks (just shows that there's more room for tinkering). Much thanks to Mike who put in a lot of effort to benchmark things and proved a worthy opponent with a competing patch. Signed-off-by: Peter Zijlstra Signed-off-by: Mike Galbraith Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed