Daniel J Blueman
2010-Nov-01 11:06 UTC
Re: btrfs and apt package manager in ubuntu (discard stalls)
On 1 November 2010 08:10, Mike Hommey <mh@glandium.org> wrote:> On Sun, Oct 31, 2010 at 11:21:36AM -0500, Christian wrote: >> On Sun, 2010-10-31 at 16:17 +0300, Abdullah Ansari wrote: >> > it''s very slow in installtion with apt in ubuntu >> >> I''m seeing the same thing. When installing using apt the disk grinds >> "forever" before the installation completes. I have two identical >> laptops running Linux Mint 10 (rc) with similar disk layout except that >> one has two btrfs partitions while the other only has ext4. The one with >> btrfs takes at least 10 times longer to install updates on than the ext4 >> one. > > That''s because dpkg uses sync when unpacking each package.I''ve seen significant stalls in dpkg calling fsync() when BTRFS discard is enabled on my OCZ Vertex SSD (firmware 1.6, Indilinx controller). I don''t get these stalls with discard on my superb Crucial C300 (Marvell controller). What is your block device and your mount options? I can reproduce an eye-watering 3.1s (!!) stall with: # sync; echo 2 >/proc/sys/vm/drop_caches; bash -x /var/lib/dpkg/info/gconf2.postinst I conclude the Vertex firmware has a performance issue. I see it is discard, as the call trace is: gconftool-2 D ffff880001e54cc0 0 4378 4377 0x00000000 ffff88010407fb98 0000000000000082 ffff88010407ffd8 0000000000014cc0 0000000000014cc0 ffff88010407ffd8 0000000000014cc0 ffff88010407ffd8 0000000000014cc0 ffff88012f115f18 ffff88012f115f20 ffff88012f115b80 Call Trace: [<ffffffff81586ade>] schedule_timeout+0x19e/0x2e0 [<ffffffff812a674e>] ? generic_make_request+0x20e/0x430 [<ffffffff815866fd>] wait_for_common+0xcd/0x180 [<ffffffff8105cd90>] ? default_wake_function+0x0/0x20 [<ffffffff812a69ed>] ? submit_bio+0x7d/0x100 [<ffffffff8158688d>] wait_for_completion+0x1d/0x20 [<ffffffff812ae339>] blkdev_issue_discard+0x1b9/0x210 [<ffffffffa0024991>] btrfs_issue_discard+0x21/0x30 [btrfs] [<ffffffffa0024a3c>] btrfs_discard_extent+0x9c/0xc0 [btrfs] [<ffffffffa002517e>] btrfs_finish_extent_commit+0x5e/0x1d0 [btrfs] [<ffffffffa0038e78>] btrfs_commit_transaction+0x4a8/0x630 [btrfs] [<ffffffff81083200>] ? autoremove_wake_function+0x0/0x40 [<ffffffffa0045635>] btrfs_sync_file+0x125/0x1a0 [btrfs] [<ffffffff8117e5a3>] vfs_fsync_range+0x83/0xa0 [<ffffffff8117e62c>] vfs_fsync+0x1c/0x20 [<ffffffff8117e66a>] do_fsync+0x3a/0x60 [<ffffffff8117e6c0>] sys_fsync+0x10/0x20 [<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b Daniel -- Daniel J Blueman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html