Re: Soft lockup by using 256K sizes

[Yan Zheng <yanzheng@21cn.com>]

2009/7/11  <oli1417@hallo.ms>:
> Hello,
>
> I just tried btrfs with a big blocksize (-n,-l,-s) of 256K. Creating =
the fs worked Ok. I had to put all three -n,-l,-s options to 256K, othe=
rwise mkfs.btrfs complained. But mounting results in a soft lockup (rep=
roducible). It's not the latest btrfs version however. The details are =
shown below.
>
> Background is the following:
>
> To upgrade the hdd of an old laptop, I used a combination of CompactF=
lash + CF-to-IDE adapter - a kind of poor-man's SSD solution. With some=
 tuning of /proc/sys/vm/dirty_X settings this is actually really Ok to =
work with. For erase block aligning I just aligned partitions to 1MiB.
>
> By experimenting with dd I found, that the best write-rates were with=
 256KiB / 512KiB blocks sizes. This let me to the wild idea to try btrf=
s with 256K block sizes, so that cow and small file packing would feed =
the CF with ideal chunks of data.
>
> Well, I don't know really whether this is supposed to work anyhow. I =
know about the ssd option, but was just curious what it would give for =
the small file packing. Anyhow ... it soft locked it ;).
>
> Cheers, Oliver
>
> mkfs.btrfs:
> ---
> # mkfs.btrfs -s 256K -n 256K -l 256K /dev/hda3
>
> WARNING! - Btrfs Btrfs v0.18 IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
>
> fs created label (null) on /dev/hda3
> =A0 =A0 =A0 =A0nodesize 262144 leafsize 262144 sectorsize 262144 size=
 4.88GB
> Btrfs Btrfs v0.18
>
> #
> ---
>
>
> kmsg:
> ---
> [ =A0447.744830] device fsid 554eb395ef55edc9-b8068222421fcb91 devid =
1 transid 9 /dev/hda3
> [ =A0513.252013] BUG: soft lockup - CPU#0 stuck for 61s! [btrfs-endio=
-met:5137]
> [ =A0513.252013] Modules linked in: btrfs zlib_deflate crc32c libcrc3=
2c sd_mod crc_t10dif usb_storage i915 drm i2c_algo_bit i2c_core binfmt_=
misc ppdev lp bnep rfcomm l2cap bluetooth michael_mic arc4 ecb lib80211=
_crypt_tkip acpi_cpufreq cpufreq_powersave cpufreq_userspace cpufreq_st=
ats cpufreq_conservative nfsd exportfs nfs lockd fscache nfs_acl auth_r=
pcgss sunrpc ext4 jbd2 crc16 fuse dm_crypt dm_snapshot cdc_ether usbnet=
 loop joydev pcmcia ipw2100 libipw snd_intel8x0m lib80211 yenta_socket =
rsrc_nonstatic pcmcia_core snd_seq_midi snd_rawmidi snd_intel8x0 snd_se=
q_midi_event snd_ac97_codec ac97_bus snd_seq snd_pcm_oss snd_mixer_oss =
snd_seq_device snd_pcm psmouse shpchp snd_timer snd soundcore serio_raw=
 snd_page_alloc rng_core dcdbas irda pcspkr pci_hotplug battery button =
evdev parport_pc parport crc_ccitt ac processor usbhid hid ext3 jbd mbc=
ache ide_cd_mod ide_gd_mod cdrom ata_generic libata uhci_hcd scsi_mod i=
de_pci_generic ehci_hcd piix intel_agp e100 mii ide_core usbcore video
> =A0output agpgart thermal fan thermal_sys dm_mirror dm_region_hash dm=
_log dm_mod
> [ =A0513.252013]
> [ =A0513.252013] Pid: 5137, comm: btrfs-endio-met Not tainted (2.6.30=
-1-686 #1) Inspiron 500m
> [ =A0513.252013] EIP: 0060:[<c031df3b>] EFLAGS: 00000246 CPU: 0
> [ =A0513.252013] EIP is at _spin_unlock_irqrestore+0x6/0xb
> [ =A0513.252013] EAX: 00000246 EBX: 00000001 ECX: f65bf5f4 EDX: 00000=
246
> [ =A0513.252013] ESI: f65bf5e0 EDI: f23c3980 EBP: f23c39a8 ESP: f2103=
f88
> [ =A0513.252013] =A0DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
> [ =A0513.252013] CR0: 8005003b CR2: b7ef56e4 CR3: 3080b000 CR4: 00000=
6d0
> [ =A0513.252013] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000=
000
> [ =A0513.252013] DR6: ffff0ff0 DR7: 00000400
> [ =A0513.252013] Call Trace:
> [ =A0513.252013] =A0[<f8839162>] ? btrfs_queue_worker+0x1d4/0x1ea [bt=
rfs]
> [ =A0513.252013] =A0[<f8838ca6>] ? worker_loop+0x73/0x1be [btrfs]
> [ =A0513.252013] =A0[<f8838c33>] ? worker_loop+0x0/0x1be [btrfs]
> [ =A0513.252013] =A0[<c0136740>] ? kthread+0x42/0x67
> [ =A0513.252013] =A0[<c01366fe>] ? kthread+0x0/0x67
> [ =A0513.252013] =A0[<c0103ab7>] ? kernel_thread_helper+0x7/0x10
> [ =A0578.748013] BUG: soft lockup - CPU#0 stuck for 61s! [btrfs-endio=
-met:5137]
> [...]
> ---
>
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current btrfs only supports blocksize =3D=3D PAGE.
(btrfs used to support large block size, but there was race in the
large blocksize code)

Yan
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