linux-kernel - Re: [git pull] vfs part 2

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Date:	Thu, 2 Jul 2015 19:56:29 +0200
From:	Dominique Martinet <dominique.martinet@....fr>
To:	Jeff Layton <jlayton@...chiereds.net>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Andrey Ryabinin <a.ryabinin@...sung.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [git pull] vfs part 2

Jeff Layton wrote on Thu, Jul 02, 2015:
> So p9_idpool_create should take an argument for the "end" value, and
> then store that in a new field in p9_idpool. Then they can pass that in
> as the "end" parm in idr_alloc. Or, they could give up using the same
> function there and use a different one for tags and FIDs.
> 
> In any case...allowing this thing to allocate tag values that can
> collide seems fundamentally wrong. Using idr_alloc_cyclic might also
> not hurt either, particularly given that these tag values are supposed
> to function something like an XID and you probably don't want to be
> reusing them too quickly.

Using cache=none here so behavious is likely different with cache, but
basically you can't get more than one tag per user thread accessing the
9P mount...
And in RDMA there's a credit so I can't get past whatever sq option was
given (defaults to 32) -- tbh even with other transports I doubt it's
going to get much higher.

Still definitely needs fixing, but I think the issue is somewhere
else... If Andrey could share the workload he uses I can try with other
servers, would be nice if we can rule a qemu bug out completely :)

-- 
Dominique
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