Messages in this thread |  | | | Date | Fri, 28 May 2004 15:45:25 -0700 | | From | Andrew Morton <> | | Subject | Re: iowait problems on 2.6, not on 2.4 |
| |
Antonio Larrosa Jiménez <antlarr@tedial.com> wrote: > > On Thursday 27 May 2004 05:52, you wrote: > > Antonio Larrosa Jiménez <antlarr@tedial.com> wrote: > > > My next test will be to do the "dd tests" on one of the internal hard > > > disks and use it for the data instead of the external raid. > > > > That's a logical next step. The reduced read bandwith on the raid array > > should be fixed up before we can go any further. I don't recall any > > reports of qlogic fc-scsi performance regressions though. > > Ok, let's analyze that first. > > The dd tests gave the following results:
Let me cc linux-scsi.
Guys: poke. Does anyone know why this:
The machine is a 4 cpu Pentium III (Cascades) system with four SCSI SEAGATE ST336704 hard disks connected to an Adaptec AIC-7899P U160/m, and a external RAID connected to a QLA2200/QLA2xxx FC-SCSI Host Bus Adapter. The machine has 1Gb RAM.
got all slow at reads?
> ext3 on the internal scsi HD: > 2.4.21: > writing : 1m14s > reading : 1m2s > reading+writing : 2m16s > 2.6.4: > writing : 1m19s > reading : 59s > reading+writing : 2m24s > > reiserfs on the internal scsi HD: > 2.4.21: > writing : 1m15s > reading : 1m1s > reading+writing : 2m22s > 2.6.4: > writing : 1m19s > reading : 1m > reading+writing : 2m25s > > ext3 on the raid using qlogic fc-scsi: > 2.4.21: > writing : 30s > reading : 51s > reading+writing : 1m29s > 2.6.4: > writing : 28s > reading : 1m26s > reading+writing : 2m19s > > reiserfs on the raid using qlogic fc-scsi: > 2.4.21: > writing : 37s > reading : 52s > reading+writing : 1m37s > 2.6.4: > writing : 25s > reading : 1m27s > reading+writing : 2m3s > > All the tests were made 3 times, and the average taken. In the cases where > there was too much variance, I repeated the tests some more times. > > All the tests used 2Gb reads/writes (. I tried to make 8Gb reads/writes too, > but they got up to a minute variance (maybe the HD slowed itself down due to > temperature issues sometimes? I really don't know why this happened, but in > any case, I couldn't make reliable tests with files of that size). > > So basically, there's no difference between 2.4.21 and 2.6.4 when using the > internal HD, but 2.6.4 is much slower when using the raid. > What I found strange is that writing to that raid is a bit faster on 2.6.4 > while reading is much slower, which I suppose is what makes the difference. > > So yes, I suppose there's a regression on the qlogic fc-scsi module. > > Btw, the tests I timed were: > > count=2048 > write() { dd if=/dev/zero of=x bs=1M count=$count ; sync } > read() { dd if=x of=/dev/null bs=1M count=$count } > readwrite() { dd if=x of=y bs=1M count=$count ; sync } > > In the case of read, I did the sync just before and after the timing, but > didn't include the sync inside the timed test. > > As I said in my other mail, I can test any patch if needed. > > Greetings and thanks for any help > > -- > Antonio Larrosa > Tecnologias Digitales Audiovisuales, S.L. > http://www.tedial.com > Parque Tecnologico de Andalucia . Málaga (Spain) > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |