On Tue, Sep 27, 2011 at 8:24 AM, Jari Kirma <[email protected]> wrote: > I recently installed Debian Squeeze on a new TS-419P+, and it ran > nicely. So, to make it more interesting, I upgraded to Wheeze, and now > I'm seeing a performance/responsiveness regression whose cause I can't > quite figure out. > > This has following symptoms: > > - Big-file dd with large block size (over 16 kiB or so, but especially > like 1 MiB), from both RAID-5 backed files and bare disks performs > much slower (30-60%!) than before. > - dd with small blocks (4 kiB would seem to be close to sweet spot) > performs roughly as expected, but slightly slower when served from > RAID-5 (maybe 25% difference at most). > - SSH and even serial console interaction on other shells feels much > choppier than it used to be according to my memory with Squeeze while > I was doing these benchmarks. > - System is fine without this disk activity (I didn't try if network > activity would have a similar effect, but just busylooping processes > cause no trouble). > > Do you have a chance to try this on Kirkwood system, preferably with > Marvell 6282, not 6281? Somehow I'm feeling that > linux-image-3.0.0-1-kirkwood kernel is missing interrupts, or > something. There is no indication of this on dmesg, though.
Also, when I perform RAID scrubbing with "echo check > /sys/block/mdX/md/sync_action", I see drastically reduced performance - down from 30-34 MB/s to 13 MB/s. Something has certainly changed. -kirma -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/cacjdtkids56ifzpjjbwtr1bcbxaysaw1lbvx5x2iml6xbm5...@mail.gmail.com
