| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 17 Jul 2006 02:20:07 +0200 From: Jens Axboe <axboe@...e.de> To: Neil Brown <neilb@...e.de> Cc: Jonathan Baccash <jbaccash@...il.com>, linux-kernel@...r.kernel.org Subject: Re: raid io requests not parallel? On Mon, Jul 17 2006, Neil Brown wrote: > On Saturday July 15, jbaccash@...il.com wrote: > > I'm using kernel linux-2.6.15-gentoo-r1, and I noticed performance of > > the software RAID-1 is not as good as I would have expected on my two > > SATA drives, and I was wondering if anyone has an idea what may be > > happening. The test I run is 1024 16k direct-IO reads/writes from > > random locations within a 1GB file (on a RAID-1 partition), with my > > disk caches set to > > write-through mode. In the MT (multi-threaded) case, I issue them from > > 8 threads (so it's 128 requests per thread): > > > > Random read: 10.295 sec > > Random write: 19.142 sec > > Odd. I would expect these two numbers to be a lot closer together. > > Try changing the IO scheduler on the drives and see if it makes a > difference. > e.g. > cat /sys/block/XXX/queue/scheduler > echo cfq > /sys/block/XXX/queue/scheduler > echo deadline > /sys/block/XXX/queue/scheduler > > See what works best. His cache is set to write through, 16kb direct writes in that case will be a lot slower than the equivalent reads. 10 vs 20 seconds does not sounds out of the question. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists