Query about slow read performance

Jeremy Allison jra at samba.org
Tue Sep 3 17:58:31 UTC 2019


On Tue, Sep 03, 2019 at 11:01:33PM +0530, Abhidnya Joshi wrote:
> Hi Jeremy,
> 
> Thanks for your reply. Yes we do see less number of credits being asked by
> problematic client compared to the other Win2k8 client.
> Is there any way to increase the number of credits client can ask for
> irrespective of tcp level delays/sizes in Win2k8?

The client is responsible for the number of
credits it requests, server is responsible for
the number of credits granted.

I wasn't easily to find a Windows registry
tunable for number of client credits requested,
but I didn't spend long searching.


> On Wed, Aug 28, 2019 at 5:20 AM Jeremy Allison <jra at samba.org> wrote:
> 
> > On Fri, Aug 23, 2019 at 12:24:34PM +0530, Abhidnya Joshi via
> > samba-technical wrote:
> > > Hi All,
> > >
> > > Recently while doing single file read testing on SMB2 from our product to
> > > Win2008 (as client), we saw some performance degradation.
> > >
> > > Although we are finding out causes in our SMB server, we can somehow see
> > > this degradation when the Win2008 got security patch applied.
> > >
> > > *2019-03 Servicing Stack Update for Windows Server 2008 R2 for x64-based
> > > Systems (KB4490628)*
> > >
> > > The performance drop is not observed for write but only for reads and the
> > > cap seen is around 260-280 Mbps. (Earlier it was around 520 Mbps). The
> > > security patch does not have anything directly related to I/O or SMB but
> > > this is what we are observing.
> > >
> > > My question here is, has anyone observed any of such problem recently
> > with
> > > Win2k8 used as client?
> >
> > Nope, this is the first I've heard of it. Can you do a comparative
> > wireshark trace between an unpatched client and a patched client
> > to look at the differences in how they're driving the server.
> >
> > Any credit changes ?
> >



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