linux-kernel - Re: [PATCH] improve the performance of large sequential write NFS workloads

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 18 Dec 2009 16:20:11 -0500
From:	Steve Rago <sar@...-labs.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <peterz@...radead.org>, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, Trond.Myklebust@...app.com,
	Wu Fengguang <fengguang.wu@...el.com>,
	"jens.axboe" <jens.axboe@...cle.com>
Subject: Re: [PATCH] improve the performance of large sequential write NFS
	workloads


On Fri, 2009-12-18 at 20:41 +0100, Ingo Molnar wrote:
> * Steve Rago <sar@...-labs.com> wrote:
> 
> > > Also, I don't think this needs to have a sysctl, it should just work.
> > 
> > The sysctl is a *good thing* in that it allows the eager writeback behavior 
> > to be tuned and shut off if need be.  I can only test the changes on a 
> > finite set of systems, so better safe than sorry.
> 
> This issue has been settled many years ago and that's not what we do in the 
> Linux kernel. We prefer patches to core code where we are reasonably sure they 
> result in good behavior - and then we fix bugs in the new behavior, if any. 
> 
> (Otherwise odd sysctls would mushroom quickly and the system would become 
> untestable in practice.)
> 
> 	Ingo

I don't disagree, but "that's not what we do" hardly provides insight
into making the judgment call.  In this case, the variety of
combinations of NFS server speed, NFS client speed, transmission link
speed, client memory size, and server memory size argues for a tunable
parameter, because one value probably won't work well in all
combinations.  Making it change dynamically based on these parameters is
more complicated than these circumstances call for, IMHO.

Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/