Chris Mason wrote:
Hello everyone,
Yan Zheng has been doing some major surgery to the back references and
extent allocation code, tackling bottlenecks in the code that tracks
extents. It scales better with many snapshots and performs better in
the common case of no snapshots at all.
THE NEW CODE IS A FORWARD ROLLING DISK FORMAT CHANGE. This means it is
compatible with the current btrfs disk format, but once you mount a
filesystem with the new code, it WILL NO LONGER BE MOUNTABLE FROM OLD
KERNELS. Old kernels spit out an error message when you try them on new
format filesystems.
This is a large change, and I'm hoping to have it stable in time for the
2.6.31 merge window. I've been testing it for about a week now, and
haven't been able to cause major problems yet. But, testing the
compatibility with old format filesystems is the hard part, and
everyone that pulls the new code should backup their data first.
I've setup git branches called newformat where you can pull the new code.
For the kernel (based on 2.6.30-rc7):
git pull git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable.git newformat
So I started the performance runs on this. The base tests completed fine
on the raid system and I will post results as soon as I can finish
postprocessing, but when I tried to do nodatacow that machine it crashed
pretty early. Here is console log:
btrfs2 kernel: [82057.882255] ------------[ cut here ]------------
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] invalid opcode: 0000 [#1] SMP
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] last sysfs file:
/sys/devices/system/cpu/cpu15/cache/index1/shared_cpu_map
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] Stack:
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] ffff88011786d800 ffff8801259f6ea0
000000b21f256030 00000000000000e9
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] 000000352231b250 ffff880089abbf40
ffff88013d0e2440 0000000000000001
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] Call Trace:
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa0445198>]
run_one_delayed_ref+0x382/0x42f [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa0464bd1>] ?
map_extent_buffer+0xab/0xbe [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa0445f75>]
run_clustered_refs+0x237/0x2b4 [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa0478f85>] ?
btrfs_find_ref_cluster+0xdc/0x115 [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:47 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa044609e>]
btrfs_run_delayed_refs+0xac/0x195 [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa044e86e>]
__btrfs_end_transaction+0x59/0xfe [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa044e92e>]
btrfs_end_transaction+0xb/0xd [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa045418b>]
btrfs_finish_ordered_io+0x224/0x24d [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa04541c4>]
btrfs_writepage_end_io_hook+0x10/0x12 [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa0467599>]
end_bio_extent_writepage+0xa3/0x18f [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff8024276e>] ?
del_timer_sync+0x14/0x20
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff802cbbee>] bio_endio+0x26/0x28
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa044b5d6>]
end_workqueue_fn+0x111/0x11e [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa046eff5>]
worker_loop+0x67/0x1ee [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffffa046ef8e>] ?
worker_loop+0x0/0x1ee [btrfs]
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff8024c324>] kthread+0x56/0x86
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff8020c9fa>] child_rip+0xa/0x20
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff8024c2ce>] ? kthread+0x0/0x86
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] [<ffffffff8020c9f0>] ? child_rip+0x0/0x20
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
btrfs2 kernel: [82057.882535] Code: 08 4c 8d 45 d4 41 8d 44 24 18 48 8b
73 20 48 8b 4d 18 41 b9 01 00 00 00 48 8b 7d b8 4c 89 ea 89 45 d4 e8 df
e3 ff ff 85 c0 74 04 <0f> 0b eb fe 49 63 75 40 4d 8b 65 00 49 83 cf 01
4c 89 e7 48 6b
Message from syslogd@ at Thu Jun 4 08:02:48 2009 ...
I also ran this on the single disk system and it did not make it through
base tests. Error are different.
[101511.664497] Pid: 28597, comm: btrfs-transacti Tainted: G D
2.6.30-rc7-autokern1 #1 IBM x3950-[88726RU]-
[101511.675497] RIP: 0010:[<ffffffff804cd70d>] [<ffffffff804cd70d>]
_spin_lock+0x14/0x1a
[101511.684494] RSP: 0018:ffff8801309bbb40 EFLAGS: 00000297
[101511.689494] RAX: 0000000000001514 RBX: ffff8801309bbb40 RCX:
ffff8801309bbb40
[101511.697493] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
ffff8800b7427d70
[101511.705491] RBP: ffffffff8020c50e R08: 0000000000000001 R09:
ffff8801309bba68
[101511.713490] R10: ffff88012231b910 R11: ffff8800478ad5b0 R12:
0000001a00000032
[101511.721488] R13: ffffffffa04370b1 R14: ffff8801309bbb60 R15:
00000000000003bf
[101511.729486] FS: 0000000000000000(0000) GS:ffff88002bac0000(0000)
knlGS:0000000000000000
[101511.738483] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[101511.744482] CR2: 00007fbcd3ff1b80 CR3: 0000000000201000 CR4:
00000000000006e0
[101511.752480] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[101511.760479] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[101511.768478] Call Trace:
[101511.771478] [<ffffffffa0471187>] ? btrfs_try_spin_lock+0x1c/0x61
[btrfs]
[101511.778476] [<ffffffffa043ea17>] ? btrfs_search_slot+0x619/0x73e
[btrfs]
[101511.786474] [<ffffffffa043f11d>] ?
btrfs_insert_empty_items+0x5e/0xa9 [btrfs]
[101511.803472] [<ffffffffa0440ce0>] ?
alloc_reserved_file_extent+0x89/0x1c3 [btrfs]
[101511.811470] [<ffffffffa04401d8>] ?
update_reserved_extents+0x98/0xab [btrfs]
[101511.819468] [<ffffffffa0445198>] ? run_one_delayed_ref+0x382/0x42f
[btrfs]
[101511.827467] [<ffffffff802a5387>] ? cache_flusharray+0xa2/0xae
[101511.833466] [<ffffffffa0445f75>] ? run_clustered_refs+0x237/0x2b4
[btrfs]
[101511.840463] [<ffffffffa0478f85>] ?
btrfs_find_ref_cluster+0xdc/0x115 [btrfs]
[101511.848462] [<ffffffff804cbdad>] ? thread_return+0x3e/0x91
[101511.854461] [<ffffffffa044609e>] ?
btrfs_run_delayed_refs+0xac/0x195 [btrfs]
[101511.862459] [<ffffffffa044f59f>] ?
btrfs_commit_transaction+0x7b/0x69c [btrfs]
[101511.870458] [<ffffffff8024c460>] ? autoremove_wake_function+0x0/0x38
[101511.877458] [<ffffffffa044ee87>] ? start_transaction+0x103/0x10f
[btrfs]
[101511.885456] [<ffffffffa044c2c6>] ? transaction_kthread+0x17f/0x20a
[btrfs]
[101511.892453] [<ffffffffa044c147>] ? transaction_kthread+0x0/0x20a
[btrfs]
[101511.900453] [<ffffffffa044c147>] ? transaction_kthread+0x0/0x20a
[btrfs]
[101511.907452] [<ffffffff8024c324>] ? kthread+0x56/0x86
[101511.912450] [<ffffffff8020c9fa>] ? child_rip+0xa/0x20
[101511.918449] [<ffffffff8024c2ce>] ? kthread+0x0/0x86
[101511.923449] [<ffffffff8020c9f0>] ? child_rip+0x0/0
[101536.249729] Pid: 28594, comm: btrfs-endio-wri Tainted: G D
2.6.30-rc7-autokern1 #1 IBM x3950-[88726RU]-
[101536.249729] RIP: 0010:[<ffffffff804cd70d>] [<ffffffff804cd70d>]
_spin_lock+0x14/0x1a
[101536.249729] RSP: 0018:ffff88011a80da80 EFLAGS: 00000297
[101536.249729] RAX: 000000000000c6c2 RBX: ffff88011a80da80 RCX:
0000000000000000
[101536.249729] RDX: 0000000000000000 RSI: ffff88013d080000 RDI:
ffff8800478ad6b0
[101536.249729] RBP: ffffffff8020c50e R08: 000000000000004c R09:
0000000000000001
[101536.249729] R10: 0000000000000008 R11: 0000000000086000 R12:
ffff88011a80da40
[101536.249729] R13: ffff8800aa254800 R14: 0000000b470c7fff R15:
ffff88011f256030
[101536.249729] FS: 0000000000000000(0000) GS:ffff88002ba30000(0000)
knlGS:0000000000000000
[101536.249729] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[101536.249729] CR2: 000000000065b078 CR3: 0000000000201000 CR4:
00000000000006e0
[101536.249729] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[101536.249729] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[101536.249729] Call Trace:
[101536.249729] [<ffffffffa04710cf>] ? btrfs_tree_lock+0x54/0x9e [btrfs]
[101536.249729] [<ffffffffa0471022>] ? btrfs_wake_function+0x0/0x10 [btrfs]
[101536.249729] [<ffffffffa0438104>] ? btrfs_lock_root_node+0x1d/0x4b
[btrfs]
[101536.249729] [<ffffffffa043e4c5>] ? btrfs_search_slot+0xc7/0x73e [btrfs]
[101536.249729] [<ffffffffa043f11d>] ?
btrfs_insert_empty_items+0x5e/0xa9 [btrfs]
[101536.249729] [<ffffffffa0444f7a>] ? run_one_delayed_ref+0x164/0x42f
[btrfs]
[101536.249729] [<ffffffffa0445f75>] ? run_clustered_refs+0x237/0x2b4
[btrfs]
[101536.249729] [<ffffffffa0478f85>] ?
btrfs_find_ref_cluster+0xdc/0x115 [btrfs]
[101536.249729] [<ffffffffa044609e>] ?
btrfs_run_delayed_refs+0xac/0x195 [btrfs]
[101536.249729] [<ffffffffa044e86e>] ?
__btrfs_end_transaction+0x59/0xfe [btrfs]
[101536.249729] [<ffffffffa044e92e>] ? btrfs_end_transaction+0xb/0xd
[btrfs]
[101536.249729] [<ffffffffa045418b>] ?
btrfs_finish_ordered_io+0x224/0x24d [btrfs]
[101536.249729] [<ffffffffa04541c4>] ?
btrfs_writepage_end_io_hook+0x10/0x12 [btrfs]
[101536.249729] [<ffffffffa0467599>] ?
end_bio_extent_writepage+0xa3/0x18f [btrfs]
[101536.249729] [<ffffffff8024276e>] ? del_timer_sync+0x14/0x20
[101536.249729] [<ffffffff802cbbee>] ? bio_endio+0x26/0x28
[101536.249729] [<ffffffffa044b5d6>] ? end_workqueue_fn+0x111/0x11e [btrfs]
[101536.249729] [<ffffffffa046eff5>] ? worker_loop+0x67/0x1ee [btrfs]
:
For the progs:
git pull git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstable.git newformat
I should mention that I missed the part about the new user tools, so
while these we newly formated filesystems, they were created with the
old tools. These are both running 64bit. I plan to install the new
tools and re-run.
Steve
The main benefit of the new code is that backrefs on the extent
allocation tree use a fuzzier format. It basically means that we search
for the key in the extent allocation tree instead of providing an exact
backref to the parent block.
This means we can predict how many blocks will be changed when changing
the extent allocation tree, and it makes enospc much less complex. It
is also significantly faster.
For regular subvolume trees, a similar change is made as long as there
are no snapshots against a given block. This is the common case, and it
makes COW less expensive overall.
Yan Zheng also worked out a way to free blocks during the transaction
without needing to do an explicit snapshot deletion on the old root when
the transaction was done. This gets rid of some complex caching code,
and fixes worst-case problems where btrfs could take a very very long
time to unmount.
btrfs-vol -b is faster with the new code as well, he added caching of
high levels in the tree to speed things up.
(Many kudos to Yan Zheng for all of this work!)
-chris
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