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SubjectRe: What is the limit size of tmpfs /dev/shm ?
Hugh Dickins wrote:
>
> In theory, yes, and should be true in practice before it hits swap.
> But I think you'll find our swap handling is too primitive for tmpfs
> to perform well once we hit swap. Most filesystems pay considerable
> attention to good performance within their constraints of correctness.
> Whereas with tmpfs we've just never worried about the performance once
> swapping. It's used so you don't lose your data, but if you're really
> expecting to be going to disk very much, better start with a filesystem
> really designed for that.
>

That sounds like a problem in our overall swap handling, not
specifically in tmpfs. Now, I can't say anything concrete about heavy
swap conditions, but in light swap conditions I have measured a 20x
performance improvement(!) over ext3 on real workloads.

-hpa


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