Re: EXT4-ish "fixes" in UBIFS

From: Trenton D. Adams
Date: Thu Apr 02 2009 - 20:54:25 EST


On Thu, Apr 2, 2009 at 6:38 PM, Christian Kujau <lists@xxxxxxxxxxxxxxx> wrote:
> On Thu, 2 Apr 2009, Trenton D. Adams wrote:
>> Oh, I should have clarified.  It improves performance under heavy
>> load.  Under normal load, mounting without sync is fine.  What I tend
>> to do is mount with "remount,rw,sync" when heavy load is starting.
>
> Really? How does mounting with "-o sync" *improve* performance? I am
> certainly aware that mounting with "-o sync" has severe performance
> impacts, but was proposing it anyway *only* to tackle the data integrity
> problem. However, I'm curious if usescaes in the embedded world are
> equally affected by this.
>

Oh, well for my system, if I do heavy IO, my *fsync* performance drops
like a rock. fsync on even 1M takes 15-20 seconds at times. I have
even seen 50 seconds. If I mount with sync option, the fsyncs of 1M
take only a couple hundred milliseconds, while the other heavy IO is
happening.
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