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On Fri, Nov 26, 2010 at 5:57 PM, Stroller |
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<stroller@××××××××××××××××××.uk> wrote: |
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> Hi there, |
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> |
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> As per subject, what's the best way to improve interactivity with heavy disk activity, please? |
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> Or perhaps a better question would be: what approaches are available? |
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> Presently my main Linux system is basically just a storage server with a *really slow* disk controller. I do all my web-browsing and email (and most other things) on my Mac laptop (because my Mac desktop has recently died ☹), but I occasionally do some bash or perl scripting, searches and other stuff on this Linux box. |
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> |
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> Normally this isn't a problem - the machine is an old Pentium 4 but plenty powerful enough for this simple command-line stuff. However I have recently bought a new STB which plays DVD .iso files across the network, so I started ripping DVDs on storage server, using dvdbackup && mkisofs. When I do so, interactivity becomes *dire* - it takes maybe 15 seconds for *any* command to execute. |
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> |
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> My immediate reaction was to consider the recent "200-line patch to kernel => superkernel" thread: |
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> http://www.gossamer-threads.com/lists/gentoo/user/221770 |
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> |
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> But I have also heard of `ionice` in the past: http://linux.die.net/man/1/ionice |
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> |
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> I've never used that - in fact, I can't recall ever having to use the regular `nice` - but I think maybe I should consider it. |
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> |
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> Does anyone have any thoughts, please? |
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> Stroller. |
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The "nice" and "ionice" or the cpu "cgroups" are not going to help a |
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lot. The problems of bad interactivity are rarely CPU related so the |
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200line patch is probably going to do nothing to help. Also "ionice" |
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rarely solves these problems, because the problem is not actually on |
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the i/o scheduler but in the page cache management of the kernel, |
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which reacts pretty bad (awful) under pressure. |
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As far as I know there is nothing you can do to fix interactivity |
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under these loads, except: |
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|
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1. From getting an SSD, that doesn't actually need page cache :) |
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2. Fix the page-management/LRU kernel code yourself :) |
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Maybe unofficial kernels (ck,zen) have improved page cache management |
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(I haven't tried them), but the issue still remains unfixed in the |
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upstream kernel. |