Re: Slow swapon for big (12GB) swap

[Andrew Morton]

Grzegorz Kulewski <kangur@xxxxxxxxxx> wrote:
>
> I am using big swap here (as a backing for potentially huge tmpfs). And I 
>  wonder why swapon on such big (like 12GB) swap takes about 7 minutes 
>  (continuous disk IO).

It's a bit quicker here:

vmm:/usr/src/25# mkswap /dev/hda6
Setting up swapspace version 1, size = 54031826 kB
vmm:/usr/src/25# time swapon /dev/hda6
swapon /dev/hda6  0.00s user 0.04s system 74% cpu 0.054 total


> Is this expected?

Nope.

> Why it is like that?

Are you using a swapfile or a swap partition?

If it's a swapfile then perhaps the filesystem is being inefficient in its
bmap() function.  Which filesystem is it?

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