On Wed, Mar 21 2007, Davide Libenzi wrote: > On Wed, 21 Mar 2007, Jens Axboe wrote: > > > On Tue, Mar 20 2007, Davide Libenzi wrote: > > > > > > I was looking at Jens FIO stuff, and I decided to cook a quick patch for > > > FIO to support GUASI (Generic Userspace Asyncronous Syscall Interface): > > > > > > http://www.xmailserver.org/guasi-lib.html > > > > > > I then ran a few tests on my Dual Opteron 252 with SATA drives (sata_nv) > > > and 8GB of RAM. > > > Mind that I'm not FIO expert, like at all, but I got some interesting > > > results when comparing GUASI with libaio at 8/1000/10000 depths. > > > If I read those result correctly (Jens may help), GUASI output is more > > > then double the libaio one. > > > Lots of context switches, yes. But the throughput looks like 2+ times. > > > Can someone try to repeat the measures and/or spot the error? > > > Or tell me which other tests to run? > > > This is kinda a suprise for me ... > > > > I don't know guasi at all, but libaio requires O_DIRECT to be async. I'm > > sure you know this, but you may not know that fio default to buffered IO > > so you have to tell it to use O_DIRECT :-) > > > > So try adding a --direct=1 (or --buffered=0, same thing) as an extra > > option when comparing depths > 1. > > I knew about AIO and O_DIRECT, but I thought FIO was using it by default :)
It actually used to, but I changed the default a few months ago as I think that is more appropriate. > I used it for the first time yesterday night, and there are a pretty wide > set of options. Will re-run today with --direct. Yep, I try to add good explanations to all of them though, also available through --cmdhelp or --cmdhelp=option so you don't have to lookup the documentation all the time. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
