From: Chengguang Xu <cgxu519@mykernel.net>
To: "Miklos Szeredi" <miklos@szeredi.hu>
Cc: "Amir Goldstein" <amir73il@gmail.com>, "Jan Kara" <jack@suse.cz>,
"overlayfs" <linux-unionfs@vger.kernel.org>,
"linux-fsdevel" <linux-fsdevel@vger.kernel.org>
Subject: Re: [RFC PATCH v2 0/8] implement containerized syncfs for overlayfs
Date: Sat, 31 Oct 2020 20:22:05 +0800 [thread overview]
Message-ID: <1757e9b90db.10c024288229.900734846219816716@mykernel.net> (raw)
In-Reply-To: <CAJfpegu-bn2BjkLaykk-gZLRv71n=PgrsrwBnuAav1GHzWO5iQ@mail.gmail.com>
---- 在 星期五, 2020-10-30 23:46:00 Miklos Szeredi <miklos@szeredi.hu> 撰写 ----
> On Sun, Oct 25, 2020 at 4:42 AM Chengguang Xu <cgxu519@mykernel.net> wrote:
> >
> > Current syncfs(2) syscall on overlayfs just calls sync_filesystem()
> > on upper_sb to synchronize whole dirty inodes in upper filesystem
> > regardless of the overlay ownership of the inode. In the use case of
> > container, when multiple containers using the same underlying upper
> > filesystem, it has some shortcomings as below.
> >
> > (1) Performance
> > Synchronization is probably heavy because it actually syncs unnecessary
> > inodes for target overlayfs.
> >
> > (2) Interference
> > Unplanned synchronization will probably impact IO performance of
> > unrelated container processes on the other overlayfs.
> >
> > This series try to implement containerized syncfs for overlayfs so that
> > only sync target dirty upper inodes which are belong to specific overlayfs
> > instance. By doing this, it is able to reduce cost of synchronization and
> > will not seriously impact IO performance of unrelated processes.
>
> Series looks good at first glance. Still need to do an in-depth review.
>
> In the meantime can you post some numbers showing the performance improvements?
>
Actually, the performance improvement depends on workload and the number of overlay instances.
I did a very simple test on my dev box (intel NUC ) and the result seems quite obvious.
I made two overlay instances and untar a kernel source to an overlay then compare
umount time(sys part) of two instances.
------------------------------------------
test env:
Intel(R) Core(TM) i7-8809G CPU @ 3.10GHz 8core
32GB memory
Samsung NVMe SSD 970 pro
test script:
[root@localhost ovl]# cat do.sh
#!/bin/sh
rm -rf upper/* &> /dev/null
echo 3 > /proc/sys/vm/drop_caches
mount -t overlay overlay -o lowerdir=lower,workdir=work,upperdir=upper merged
mount -t overlay overlay -o lowerdir=lower2,workdir=work2,upperdir=upper2 merged2
tar Jxvf linux-5.9.tar.xz -C merged &> /dev/null
time umount merged2
time umount merged
---------------------------------
test result:
[root@localhost ovl]# seq 3 | while read line ; do sh -x do.sh ; done
+ rm -rf upper/linux-5.9
+ echo 3
+ mount -t overlay overlay -o lowerdir=lower,workdir=work,upperdir=upper merged
+ mount -t overlay overlay -o lowerdir=lower2,workdir=work2,upperdir=upper2 merged2
+ tar Jxvf linux-5.9.tar.xz -C merged
+ umount merged2
real 0m0.437s
user 0m0.001s
sys 0m0.001s
+ umount merged
real 0m2.107s
user 0m0.002s
sys 0m0.090s
+ rm -rf upper/linux-5.9
+ echo 3
+ mount -t overlay overlay -o lowerdir=lower,workdir=work,upperdir=upper merged
+ mount -t overlay overlay -o lowerdir=lower2,workdir=work2,upperdir=upper2 merged2
+ tar Jxvf linux-5.9.tar.xz -C merged
+ umount merged2
real 0m0.443s
user 0m0.002s
sys 0m0.001s
+ umount merged
real 0m2.032s
user 0m0.001s
sys 0m0.105s
+ rm -rf upper/linux-5.9
+ echo 3
+ mount -t overlay overlay -o lowerdir=lower,workdir=work,upperdir=upper merged
+ mount -t overlay overlay -o lowerdir=lower2,workdir=work2,upperdir=upper2 merged2
+ tar Jxvf linux-5.9.tar.xz -C merged
+ umount merged2
real 0m0.263s
user 0m0.001s
sys 0m0.001s
+ umount merged
real 0m2.094s
user 0m0.000s
sys 0m0.083s
[root@localhost o
Thanks,
Chengguang
prev parent reply other threads:[~2020-10-31 12:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-25 3:41 [RFC PATCH v2 0/8] implement containerized syncfs for overlayfs Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 1/8] ovl: setup overlayfs' private bdi Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 2/8] ovl: implement ->writepages operation Chengguang Xu
2020-11-02 17:17 ` Jan Kara
2020-11-04 12:18 ` Chengguang Xu
2020-11-05 13:55 ` Jan Kara
2020-11-06 5:57 ` Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 3/8] ovl: implement overlayfs' ->evict_inode operation Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 4/8] ovl: mark overlayfs' inode dirty on modification Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 5/8] ovl: mark overlayfs' inode dirty on shared writable mmap Chengguang Xu
2020-11-02 17:30 ` Jan Kara
2020-11-04 11:54 ` Chengguang Xu
2020-11-05 14:03 ` Jan Kara
2020-11-05 14:21 ` Amir Goldstein
2020-11-05 15:54 ` Jan Kara
2020-11-06 2:41 ` Chengguang Xu
2020-11-06 8:50 ` Jan Kara
2020-11-06 9:47 ` Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 6/8] ovl: implement overlayfs' ->write_inode operation Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 7/8] ovl: cache dirty overlayfs' inode Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 8/8] ovl: implement containerized syncfs for overlayfs Chengguang Xu
2020-10-30 15:46 ` [RFC PATCH v2 0/8] " Miklos Szeredi
2020-10-31 12:22 ` Chengguang Xu [this message]
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