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Date: Fri, 29 Mar 2013 15:32:53 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: Jan Kara <jack@...e.cz>
Cc: Theodore Ts'o <tytso@....edu>, Eric Sandeen <sandeen@...hat.com>,
Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: fix ext4_evict_inode() racing against workqueue
processing code
On Tue, Mar 26, 2013 at 09:34:03PM +0100, Jan Kara wrote:
> On Tue 26-03-13 13:52:51, Zheng Liu wrote:
> > Sorry for the late reply.
> >
> > On Wed, Mar 20, 2013 at 10:45:23AM -0400, Theodore Ts'o wrote:
> > > On Wed, Mar 20, 2013 at 09:14:42AM -0500, Eric Sandeen wrote:
> > > >
> > > > As an aside, is there any reason to have "dioread_nolock" as an option
> > > > at this point? If it works now, would you ever *not* want it?
> > > >
> > > > (granted it doesn't work with some journaling options etc, but that
> > > > behavior could be automatic, w/o the need for special mount options).
> > >
> > > The primary restriction is that diread_nolock doesn't work when fs
> > > block size != page size. If your proposal is that we automatically
> > > enable diread_nolock when we can use it safely, that's definitely
> > > something to consider for the next merge window.
> >
> > Yes, I also think we can automatically enable dioread_nolock because it
> > brings us some benefits.
> But isn't there also some overhead due to buffered writes having to go
> through uninit->init conversion?
Hi Jan,
Here is my test result. I use fio to do some performance tests. The
test environment is a Dell desktop with a Intel(R) Core(TM)2 Duo CPU
E8400 @ 3.00GHz, 4G memory, 1 Intel 320 SSD. I test three cases that
are sync dio read/write, aio dio read/write, and sync buffered io.
The result is as below. Due to too many number we post some key data
here.
>From the result we can see that after dioread_nolock enables the max
latency can be reduced dramatically for sync dio and sync bio, and other
value doesn't be affected too much. If I miss some important test case,
please let me know.
Thanks,
- Zheng
The kernel version is 3.9.0-rc4+.
= sync dio =
== fio config file ==
[global]
ioengine=psync
direct=1
bs=4k
thread
group_reporting
directory=/mnt/sda1/
filename=testfile
filesize=10g
size=10g
runtime=120
iodepth=16
fallocate=0
[reader]
rw=randread
numjobs=8
[writer]
rw=randwrite
numjobs=2
== result ==
=== w/o dioread_nolock ===
read : io=5142.1MB, bw=43885KB/s, iops=10971 , runt=120002msec
clat (usec): min=123 , max=679911 , avg=727.21, stdev=3986.35
lat (usec): min=123 , max=679911 , avg=727.40, stdev=3986.35
write: io=542548KB, bw=4521.2KB/s, iops=1130 , runt=120003msec
clat (usec): min=136 , max=2743.3K, avg=1766.78, stdev=14844.10
lat (usec): min=137 , max=2743.3K, avg=1767.14, stdev=14844.10
=== w/ dioread_nolock ===
read : io=5072.2MB, bw=43282KB/s, iops=10820 , runt=120002msec
clat (usec): min=158 , max=291847 , avg=737.38, stdev=3944.14
lat (usec): min=158 , max=291848 , avg=737.56, stdev=3944.14
write: io=589752KB, bw=4914.6KB/s, iops=1228 , runt=120001msec
clat (usec): min=138 , max=2048.3K, avg=1625.15, stdev=11344.36
lat (usec): min=139 , max=2048.3K, avg=1625.50, stdev=11344.35
= aio dio =
== fio config file ==
[global]
ioengine=libaio
direct=1
bs=4k
thread
group_reporting
directory=/mnt/sda1/
filename=testfile
filesize=10g
size=10g
runtime=120
iodepth=64
fallocate=0
[reader]
rw=randread
numjobs=8
[writer]
rw=randwrite
numjobs=2
== result ==
=== w/o dioread_nolock ===
read : io=4865.4MB, bw=41510KB/s, iops=10377 , runt=120014msec
slat (usec): min=3 , max=320273 , avg=700.79, stdev=6070.93
clat (usec): min=232 , max=958452 , avg=48627.21, stdev=53296.33
lat (usec): min=248 , max=958471 , avg=49328.36, stdev=53905.27
write: io=684100KB, bw=5700.3KB/s, iops=1425 , runt=120013msec
slat (usec): min=5 , max=349019 , avg=1339.75, stdev=9538.63
clat (usec): min=140 , max=1060.1K, avg=88459.40, stdev=95903.63
lat (usec): min=211 , max=1060.1K, avg=89799.48, stdev=97025.95
=== w/ dioread_nolock ===
read : io=4869.1MB, bw=41544KB/s, iops=10385 , runt=120037msec
slat (usec): min=4 , max=322951 , avg=700.33, stdev=5987.29
clat (usec): min=229 , max=703241 , avg=48584.27, stdev=52570.02
lat (usec): min=248 , max=703247 , avg=49284.94, stdev=53185.97
write: io=698856KB, bw=5821.1KB/s, iops=1455 , runt=120038msec
slat (usec): min=7 , max=367042 , avg=1297.87, stdev=9316.21
clat (usec): min=178 , max=968434 , avg=86625.80, stdev=92500.21
lat (usec): min=284 , max=1020.8K, avg=87924.01, stdev=93554.86
= sync buffered io =
== fio config file ==
[global]
ioengine=psync
direct=0
bs=4k
thread
group_reporting
directory=/mnt/sda1/
filename=testfile
filesize=10g
size=10g
runtime=120
iodepth=16
fallocate=0
[reader]
rw=randread
numjobs=8
[writer]
rw=randwrite
numjobs=2
== result ==
=== w/o dioread_nolock ===
read : io=7577.6MB, bw=64661KB/s, iops=16165 , runt=120001msec
clat (usec): min=1 , max=3107.8K, avg=493.15, stdev=5368.87
lat (usec): min=1 , max=3107.8K, avg=493.31, stdev=5368.87
write: io=764256KB, bw=6350.2KB/s, iops=1587 , runt=120353msec
clat (usec): min=2 , max=42443K, avg=1257.41, stdev=138832.28
lat (usec): min=2 , max=42443K, avg=1257.57, stdev=138832.29
=== w/ dioread_nolock ===
read : io=7613.1MB, bw=64972KB/s, iops=16243 , runt=120001msec
clat (usec): min=1 , max=1126.4K, avg=490.79, stdev=3742.64
lat (usec): min=1 , max=1126.4K, avg=490.95, stdev=3742.64
write: io=763428KB, bw=6351.1KB/s, iops=1587 , runt=120189msec
clat (usec): min=2 , max=45783K, avg=1258.23, stdev=163258.23
lat (usec): min=2 , max=45783K, avg=1258.37, stdev=163258.23
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