From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4A73107B.8030102@seanodes.com> Date: Fri, 31 Jul 2009 17:40:43 +0200 From: Ivan Frain MIME-Version: 1.0 Subject: Re: problem with the "write_bw_log" parameter in a virtualized environment using a write iopattern References: <4A72AF0E.7070005@seanodes.com> <20090731092127.GO12579@kernel.dk> In-Reply-To: <20090731092127.GO12579@kernel.dk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable To: Jens Axboe Cc: fio@vger.kernel.org List-ID: Jens Axboe a =C3=A9crit : > On Fri, Jul 31 2009, Ivan Frain wrote: > >> Hi everybody, >> >> I'am using fio in a vmware virtualized environment. I have got a guest >> virtual machine based on centos5.2 on which I run fio in order to >> measure the virtual disks IO performances. >> I use the "write_bw_log" parameter in order to build graphs for the >> experiments but the problem is that the file generated by fio for each >> job is empty (size =3D 0). >> However, i also use "write_clat_log" parameter and the 'clat.log' and >> 'slat.log' files are not empty. The mean bandwidth in the fio output >> summary seams to be good. >> > > I wonder how long that bug has been there... It's due to a botched > memcpy in the fio core. There are two stat sample times, yet it > overwrites only the first one (being 0, or DDIR_READ, which explains why > the read one works). > > Try the below patch, it's also committed now. > > diff --git a/fio.c b/fio.c > index ba9e384..7ad1b57 100644 > --- a/fio.c > +++ b/fio.c > @@ -1105,7 +1105,10 @@ static void *thread_main(void *data) > clear_state =3D 0; > while (keep_running(td)) { > fio_gettime(&td->start, NULL); > - memcpy(&td->ts.stat_sample_time, &td->start, sizeof(td->start)); > + memcpy(&td->ts.stat_sample_time[0], &td->start, > + sizeof(td->start)); > + memcpy(&td->ts.stat_sample_time[1], &td->start, > + sizeof(td->start)); > memcpy(&td->tv_cache, &td->start, sizeof(td->start)); > > if (td->o.ratemin[0] || td->o.ratemin[1]) > > Well, this patch works very well, the bw log file is filled again. Thank you for your quick answer. FIO rocks !! Best regards, Ivan Frain -- *Seanodes* B=C3=A2timent Platon 25 boulevard Victor Hugo 31770 Colomiers t=C3=A9l : 05.62.12.00.19 http://www.seanodes.com