Messages in this thread | | | Date | Thu, 09 Aug 2007 12:57:11 +1200 | From | Greg Trounson <> | Subject | Re: [PATCH 00/23] per device dirty throttling -v8 |
| |
Ingo Molnar wrote: > * Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: > >>>> People just need to know about the performance differences - very >>>> few realise its more than a fraction of a percent. I'm sure Gentoo >>>> will use relatime the moment anyone knows its > 5% 8) >>> noatime,nodiratime gave 50% of wall-clock kernel rpm build >>> performance improvement for Dave Jones, on a beefy box. Unless i >>> misunderstood what you meant under 'fraction of a percent' your >>> numbers are _WAY_ off. >> What numbers - I didn't quote any performance numbers ? > > ok, i misunderstood your "very few realise its more than a fraction of a > percent" sentence, i thought you were saying it's a fraction of a > percent. > > Measurements show that noatime helps 20-30% on regular desktop > workloads, easily 50% for kernel builds and much more than that (in > excess of 100%) for file-read-intense workloads. We cannot just walk > past such a _huge_ performance impact so easily without even reacting to > the performance arguments, and i'm happy Ubuntu picked up > noatime,nodiratime and is whipping up the floor with Fedora on the > desktop. >
Sorry I'm just not seeing those gains here. With my filesystems mounted with atime defaults the Quake sources build in 1m28.856s. A test with ls -ltu verifies that atime is working as expected. When I remount my filesystems with: mount [fs] -o remount,noatime,nodiratime I get a compile time of 1m23.368s, a mere 6% improvement.
This is on a dual-core Athlon 4200+ box running 2.6.21, so I would have thought this to be close to a best-case file I/O test.
Greg - 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/
| |