Re: kswapd in tight loop 2.6.9-rc3-bk-recent

From: Dave Jones
Date: Thu Oct 07 2004 - 16:48:05 EST


On Thu, Oct 07, 2004 at 02:20:19PM -0700, Chris Wright wrote:
> Is this known? Just came back from lunch, so I've no clue what kicked it
> off. Profile below. (2.6.9-rc3-bk from yesterday, pending updates don't
> appear to touch vmscan or mm/ in general).
>
> CPU: AMD64 processors, speed 1994.35 MHz (estimated)
> Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a
> unit mask
> of 0x00 (No unit mask) count 100000
> samples % symbol name
> 2410135 53.4092 balance_pgdat
> 1328186 29.4329 shrink_zone
> 555121 12.3016 shrink_slab
> 84942 1.8823 __read_page_state
> 40770 0.9035 timer_interrupt

I saw the same thing yesterday, also on an amd64 box though that
could be coincidence. The kswapd1 process was pegging the cpu at 99%
kswapd0 was idle. After a few minutes, the box became so unresponsive
I had to reboot it.

I had put this down to me fiddling with some patches, and it hasnt'
reappeared today yet, but it sounds like we're seeing the same thing.

Sadly, I didn't get a profile of what was happening.
A 'make allmodconfig' triggered it for me, on a box with 2GB of ram,
and 2GB of swap. No swap was in use when things 'went wierd', and
there was a bunch of RAM sitting free too (about half a gig if memory
serves correctly)

Dave

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