Subject: Re: msdosfs performance problem
To: None <tech-kern@netbsd.org>
From: Christos Zoulas <christos@astron.com>
List: tech-kern
Date: 11/28/2005 00:24:06
In article <Pine.BSF.4.51.0511271619350.75650@vegeta.city-net.com>,
Matthew Orgass  <darkstar@city-net.com> wrote:
>On 2005-11-27 mlelstv@serpens.de wrote:
>> darkstar@city-net.com (Matthew Orgass) writes:
>>
>> >  msdosfs does all writes fully synchronously (why, I can't say).
>>
>> As I understand it meta data writes are synchronous but
>> can be asynchronous if you mount -o async. Data writes
>> are done by UBC and are asynchronous.
>
>  You are right, it isn't fully synchronous. I should have tested it more
>(checking directly now does show serious performance loss with -o sync).
>However it doesn't seem to behave quite like normal ffs in that all data
>will be flushed before the writing command completes, and dd seems to show
>accurate times early in the transfer.

And performance degrades dramatically as the file size increases.

christos