Re: No, really, stop trying to delete slab until you've finished making slub perform as well

From: KOSAKI Motohiro
Date: Tue Aug 05 2008 - 08:09:11 EST

> KOSAKI Motohiro wrote:
>
> > When hackbench running, SLUB consume memory very largely than SLAB.
> > then, SLAB often outperform SLUB in memory stavation state.
> >
> > I don't know why memory comsumption different.
> > Anyone know it?
>
> Can you quantify the difference?

machine spec:
CPU: IA64 x 8
MEM: 8G (4G x2node)

test method

1. echo 3 >/proc/sys/vm/drop_caches
2. % ./hackbench 90 process 1000 <- for fill pagetable cache
3. % ./hackbench 90 process 1000


vmstat result

<SLAB (without CONFIG_DEBUG_SLAB)>

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
2 0 0 3223168 6016 38336 0 0 0 0 3181 4314 0 15 85 0 0
2039 2 0 2022144 6016 38336 0 0 0 0 2364 13622 0 49 51 0 0
634 0 0 2629824 6080 38336 0 0 0 64 83582 2538927 5 95 0 0 0
596 0 0 2842624 6080 38336 0 0 0 0 6864 675841 6 94 0 0 0
590 0 0 2993472 6080 38336 0 0 0 0 9514 456085 6 94 0 0 0
503 0 0 3138560 6080 38336 0 0 0 0 8042 276024 4 96 0 0 0

about 3G remain.

<SLUB>
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
1066 0 0 323008 3584 18240 0 0 0 0 12037 47353 1 99 0 0 0
1101 0 0 324672 3584 18240 0 0 0 0 6029 25100 1 99 0 0 0
913 0 0 330240 3584 18240 0 0 0 0 9694 54951 2 98 0 0 0

about 300M remain.


So, about 2.5G - 3G difference in 8G mem.




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