Messages in this thread | | | Date | Thu, 29 Apr 2004 13:42:22 -0700 | From | Andrew Morton <> | Subject | Re: ~500 megs cached yet 2.6.5 goes into swap hell |
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Andy Isaacson <adi@hexapodia.org> wrote: > > What I want is for purely sequential workloads which far exceed cache > size (dd, updatedb, tar czf /backup/home.nightly.tar.gz /home) to avoid > thrashing my entire desktop out of memory. I DON'T CARE if the tar > completed in 45 minutes rather than 80. (It wouldn't, anyways, because > it only needs about 5 MB of cache to get every bit of the speedup it was > going to get.) But the additional latency when I un-xlock in the > morning is annoying, and there is no benefit.
What kernel version are you using? If 2.6, what value of /proc/sys/vm/swappiness?
> For a more useful example, ideally I *should not be able to tell* that > "dd if=/hde1 of=/hdf1" is running.
I just did a 4GB `dd if=/dev/sda of=/x bs=1M' on a 1GB 2.6.6-rc2-mm2 swappiness=85 machine here and there was no swapout at all.
Probably your machine has less memory. But without real, hard details nothing can be done.
> There is *no* benefit to cacheing > more than about 2 pages, under this workload.
Sure, we could do better things with the large streaming files, although the risk of accidentally screwing up particular workloads is high.
But the use-once logic which we have in there at present does handle these cases quite well.
> But with current kernels, > IME, that workload results in a gargantuan buffer cache and lots of > swapout of apps I was using 3 minutes ago. I've taken to walking away > for some coffee, coming back when it's done, and "sudo swapoff > /dev/hda3; sudo swapon -a" to avoid the latency that is so annoying when > trying to use bloaty apps.
What kernel, what system specs, what swappiness setting? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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