On Fri, May 10, 2013 at 10:59:22PM +0200, Paolo Bonzini wrote: > Il 10/05/2013 19:41, Anthony Liguori ha scritto: > > Paolo Bonzini <pbonz...@redhat.com> writes: > > > >> Il 10/05/2013 16:39, Anthony Liguori ha scritto: > >>> I just oppose the notion of disabling casts and *especially* only > >>> disabling casts for official builds. > >> > >> This actually happens all the time. Exactly this kind of type-safe cast > >> is disabled in releases of GCC, but enabled when building from svn trunk. > > > > Let's assume for a moment that you are right and this behavior is what > > we should have. Let's also assume there is a real regression here > > which has yet to have been established. > > Aurelien timed the effect of my patch two hours before you sent this > message. If it's not a regression in 1.5 (which is quite obvious from > the profile), it is a regression from the introduction of CPU classes > (1.3 or 1.4), when this code didn't exist at all. > > And in 1.5 we introduced virtio-net casts as well (or did mst sneak in > his change anyway? ;)). If 10% is the effect of a few hundred > interrupts/sec, perhaps the same effect is visible on a few thousand > packets/sec. I wouldn't bet against that one week from release.
I have run perf top on a KVM x86-64 instance running iperf. I measured around 3% of the CPU taken by g_hash_table_lookup + g_str_hash + __strcmp_sse42. I don't know how it was before though. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net http://www.aurel32.net