Anthony Liguori wrote: > Avi Kivity wrote: >> Anthony Liguori wrote: >> >> [updated patch] >> >> Applied. >> >> >>> Hard to say exactly because of the noise. I did two runs of 4 >>> test/vmexit: >>> >>> Before 4091, 4194, 4559, 4439 >>> After: 3979, 4324, 3918, 3910 >>> >>> So there's definitely a speedup, but probably only 100-200 cycles. >>> >>> >> >> Running on an idle, headless server with the vcpu pinned reduces >> variability to a few cycles in the after case. Strangely, the >> variability is high in the before case. I get a similar disappointing >> result of 100-200 cycles. >> > > I previously measured how long fx_save/fx_restore took and it was > right around 150 cycles on AMD.
Well, we're calling it twice per vmexit. A save/restore pair is 313 cycles on a Woodcrest; two of those make 626 out of ~4000 cycles should get us a nice 15% gain. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
