On Thursday, November 29, 2012 03:56:10 PM Gleb Natapov wrote: > On Thu, Nov 29, 2012 at 03:45:52PM +0200, George-Cristian Bîrzan wrote: > > On Thu, Nov 29, 2012 at 1:56 PM, Vadim Rozenfeld <vrozenfe@xxxxxxxxxx> wrote: > > >> I've also added +hv_relaxed since then, but this is the command I'm > > > > > > I would suggest activating relaxed timing for all W2K8R2/Win7 guests. > > > > Is there any place I can read up on the downsides of this for Linux, > > or is Just Better? > > You shouldn't use hyper-v flags for Linux guests. In theory Linux should > just ignore them, in practice there may be bugs that will prevent Linux > from detecting that it runs as a guest and disable optimizations. > As Gleb said, hyper-v flag are relevant to the Windows guests only. IIRC spinlocks and vapic should work for Vista and higher. Relaxed timing and partition reference time work for Win7/W2K8R2. > > >>>> Other than that, was looking into a profiling trace of the software > > >> > > >> running and a lot of time (60%?) is spent calling two functions from > > >> hal.dll, HalpGetPmTimerSleepModePerfCounter when I disable HPET, and > > >> HalpHPETProgramRolloverTimer which do point at something related to > > >> the timers. > > > > > > It means that hyper-v time stamp source was not activated. > > > > I recompiled the whole kernel, with your patch, and while I cannot > > check at 70Mbps now, a test stream of 20 seems to do better. Also, now > > I don't see any of those functions, which used to account ~60% of the > > time spent by the program. I'm waiting for the customer to come back > > and start the 'real' stream, but from my tests, time spent in hal.dll > > is now an order of magnitude smaller. > > > > -- > > George-Cristian Bîrzan > > -- > Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
