On Mon, Sep 6, 2010 at 7:47 PM, Mel Gorman <mel@xxxxxxxxx> wrote:
<snip>
>
> These are just the raw figures taken from /proc/vmstat. It's a rough measure
> of reclaim activity. Note that allocstall counts are higher because we
> are entering direct reclaim more often as a result of not sleeping in
> congestion. In itself, it's not necessarily a bad thing. It's easier to
> get a view of what happened from the vmscan tracepoint report.
>
> FTrace Reclaim Statistics: vmscan
> micro-traceonly-v1r5-micromicro-nocongest-v1r5-micromicro-lowlumpy-v1r5-micromicro-nodirect-v1r5-micro
> traceonly-v1r5 nocongest-v1r5 lowlumpy-v1r5 nodirect-v1r5
> Direct reclaims 152 941 967 729
> Direct reclaim pages scanned 507377 1404350 1332420 1450213
> Direct reclaim pages reclaimed 10968 72042 77186 41097
> Direct reclaim write file async I/O 0 0 0 0
> Direct reclaim write anon async I/O 0 0 0 0
> Direct reclaim write file sync I/O 0 0 0 0
> Direct reclaim write anon sync I/O 0 0 0 0
> Wake kswapd requests 127195 241025 254825 188846
> Kswapd wakeups 6 1 1 1
> Kswapd pages scanned 4210101 3345122 3427915 3306356
> Kswapd pages reclaimed 2228073 2165721 2143876 2194611
> Kswapd reclaim write file async I/O 0 0 0 0
> Kswapd reclaim write anon async I/O 0 0 0 0
> Kswapd reclaim write file sync I/O 0 0 0 0
> Kswapd reclaim write anon sync I/O 0 0 0 0
> Time stalled direct reclaim (seconds) 7.60 3.03 3.24 3.43
> Time kswapd awake (seconds) 12.46 9.46 9.56 9.40
>
> Total pages scanned 4717478 4749472 4760335 4756569
> Total pages reclaimed 2239041 2237763 2221062 2235708
> %age total pages scanned/reclaimed 47.46% 47.12% 46.66% 47.00%
> %age total pages scanned/written 0.00% 0.00% 0.00% 0.00%
> %age file pages scanned/written 0.00% 0.00% 0.00% 0.00%
> Percentage Time Spent Direct Reclaim 43.80% 21.38% 22.34% 23.46%
> Percentage Time kswapd Awake 79.92% 79.56% 79.20% 80.48%
There is a nitpick about stalled reclaim time.
For example, In direct reclaim
===
trace_mm_vmscan_direct_reclaim_begin(order,
sc.may_writepage,
gfp_mask);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
===
In this case, Isn't this time accumulated value?
My point is following as.
Process A Process B
direct reclaim begin
do_try_to_free_pages
cond_resched
direct reclaim begin
do_try_to_free_pages
direct reclaim end
direct reclaim end
So A's result includes B's time so total stall time would be bigger than real.
--
Kind regards,
Minchan Kim
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