Re: Samba speed

[Volker Lendecke <Volker.Lendecke@SerNet.DE>]

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On Tue, Dec 09, 2008 at 01:55:09AM -0500, Theodore Tso wrote:
> On Tue, Dec 09, 2008 at 05:25:29PM +1100, ronnie sahlberg wrote:
> > 
> > Its not as simple as "the redirector does it every 128k".   the
> > redirector does this but it varies from run to run and from client to
> > client.
> > It is very common to see this happening in 60-64kb strides   and other
> > strides as well.
> > 
> > It is probably some interaction with how large the actual i/o that the
> > application did internally to the cache and some other thing.
> > but anyway, it varies a lot. it is not always 128k.
> 
> Is there a maximum stride size used by the redirector?  i.e., will it
> use something bigger than 128k?  In any case, increasing the ext3
> reservation window size should still be helpful.  It's OK if we
> increase it to 32 blocks (128k, on a 4k block filesystem), and the
> stride size is smaller than that.  But if it is often bigger than
> 128k, then then it would probably be better if samba used the
> EXT3_IOC_SETRSVSZ ioctl to dynamically set the reservation size as
> appropriate.

One might try to use "dd" from Cygwin on Windows. When I
once analyzed this behaviour, the 1-byte writes were exactly
at the end of the block the Win32 app gave to the kernel as
seen by the sysinternals filemon tool.

Volker

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