* Linus Torvalds <[EMAIL PROTECTED]> wrote: > On Fri, 3 Aug 2007, Peter Zijlstra wrote: > > > > These patches aim to improve balance_dirty_pages() and directly address > > three > > issues: > > 1) inter device starvation > > 2) stacked device deadlocks > > 3) inter process starvation > > Ok, the patches certainly look pretty enough, and you fixed the only > thing I complained about last time (naming), so as far as I'm > concerned it's now just a matter of whether it *works* or not. I guess > being in -mm will help somewhat, but it would be good to have people > with several disks etc actively test this out.
There are positive reports in the never-ending "my system crawls like an XT when copying large files" bugzilla entry: http://bugzilla.kernel.org/show_bug.cgi?id=7372 " vfs_cache_pressure=1 TCQ nr_requests 8 128 not that bad 1 128 snappiest configuration, almost no pauses (or unnoticable ones) " " 1) vfs_cache_pressure at 100, 2.6.21.5+per bdi throttling patch Result is good, not as snappier as I'd want during a large copy but still usable. No process seems stuck for agen, but there seems to be some short (second or subsecond) moment where everything is stuck (like if you run a top d 0.5, the screen is not updated on a regular basis). 2) vfs_cache_pressure at 1, 2.6.21.5+per bdi throttling patch Result is at 2.6.17 level. It is the better combination since 2.6.17. " " 1) I've applied the patches posted by Peter Zijlstra in comment #76 to the 2.6.21-mm2 kernel to check if it removes the problem. My impression is that the problem is still there with those patches, although less visible then with the clean 2.6.21 kernel. " so the whole problem area seems to be a "perfect storm" created by a combination of TCQ, IO scheduling and VM dirty handling weaknesses. Per device dirty throttling is a good step forward and it makes a very visible positive difference. Ingo - 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/
