|From:||Linus Torvalds <torvalds-AT-linux-foundation.org>|
|To:||"Trenton D. Adams" <trenton.d.adams-AT-gmail.com>|
|Subject:||Re: [PATCH 0/8][RFC] IO latency/throughput fixes|
|Date:||Mon, 6 Apr 2009 22:02:03 -0700 (PDT)|
|Cc:||Chris Mason <chris.mason-AT-oracle.com>, Theodore Tso <tytso-AT-mit.edu>, Hua Zhong <hzhong-AT-gmail.com>, Jens Axboe <jens.axboe-AT-oracle.com>, Linux Kernel Mailing List <linux-kernel-AT-vger.kernel.org>|
On Mon, 6 Apr 2009, Trenton D. Adams wrote: > > What about a procfs setting instead? Is there a policy about why > something should be in procfs or /sys, or as a kernel config option? > That's basically as small as the patch you just made, right? I'm never really against making things dynamically tunable, but this already was, and that wasn't really the issue. Sure, you can just re-mount your filesystem with different options. That's what I did while testing - my /home is on a drive of its own, so I would just log out and as root unmount and re-mount with data=ordered/writeback, and log in and test again. So dynamic tuning is good. But at the same time, having a tuning option is _never_ an excuse for not getting the default right in the first place. It's just a cop-out to say "hey, the default may be wrong for you, but you can always tune it locally with XYZ". The thing is, almost nobody does that. Partly because it needs effort and knowledge, partly because after a few years the number of tuning knobs are in the hundreds for every little thing. So instead, leave the tuning for the _really_ odd cases (if you use your machine as an IP router, you hopefully know enough to tune it if you really care). Not for random general-purpose "use for whatever" kind of thing. > I'm just thinking that something like this, where people want one > thing or the other, but may not know it when they install Linux, might > like to change it realtime. Especially if they are a Linux newbie, > and don't know how to compile their own kernel. Or don't have time to > maintain their own kernel installs. Oh absolutely. I'm not expecting people to compile their own kernels. I'm expecting that within a few months, most modern distributions will have (almost by mistake) gotten a new set of saner defaults, and anybody who keeps their machine up-to-date will see a smoother experience without ever even realizing _why_. Linus
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