From: Andi Kleen <andi@firstfloor.org>
To: Premysl Kouril <premysl.kouril@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: EXT4 vs LVM performance for VMs
Date: Thu, 11 Feb 2016 22:12:19 -0800 [thread overview]
Message-ID: <87twlee9to.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <CA+rfnd+HnbFLR16iRyvAuFwwAWmBDM2SNNGodMbeKZf-G_9p2A@mail.gmail.com> (Premysl Kouril's message of "Thu, 11 Feb 2016 21:50:58 +0100")
Premysl Kouril <premysl.kouril@gmail.com> writes:
>
> So basically we attribute the lower EXT4 performance to these points
> where things need to be synchronized using locks but this is just what
> we see at high level so I would be curious if dev community thinks
> this might be the cause.
Except for the last the backtraces you're showing are for futex locks,
which are not used by the kernel, but some user process. So the locking
problem is somewhere in the user space setup (perhaps in qemu).
This would indicate your ext4 set up is not the same as LVM.
The later is the inode mutex which is needed for POSIX semantics
to get atomic writes.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2016-02-12 6:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-11 20:50 EXT4 vs LVM performance for VMs Premysl Kouril
2016-02-12 6:12 ` Andi Kleen [this message]
2016-02-12 9:09 ` Premysl Kouril
2016-02-12 13:38 ` Theodore Ts'o
2016-02-12 14:13 ` Premysl Kouril
2016-02-12 16:53 ` Theodore Ts'o
2016-02-12 17:38 ` Premysl Kouril
2016-02-13 2:15 ` Dave Chinner
2016-02-13 21:56 ` Sanidhya Kashyap
2016-02-13 23:40 ` Jaegeuk Kim
2016-02-14 0:01 ` Dave Chinner
2016-02-15 18:56 ` Premysl Kouril
2016-02-15 19:11 ` Liu Bo
2016-02-15 23:10 ` Dave Chinner
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