On Fri 01-06-12 10:37:30, Michal Hocko wrote:
[...]
> More detailed statistics (max/min - the worst/best performance).
> comparison (cong is 100%) comparison (page reclaim 100%)
> max min median max min median
> * ext3
> ** Write
> 5M 171.20% 95.33% 98.70% 216.96% 101.99% 103.61%
> 60M 97.56% 98.80% 104.51% 110.09% 100.11% 116.59%
> 300M 99.76% 99.49% 99.35% 99.47% 99.89% 99.57%
> 2G 99.52% 99.53% 99.52% 100.09% 99.07% 100.02%
>
> ** Read
> 5M 35.37% 38.70% 39.09% 83.55% 89.85% 86.54%
> 60M 89.70% 102.90% 102.00% 97.71% 101.91% 102.06%
> 300M 92.38% 99.33% 99.14% 80.65% 98.39% 91.23%
> 2G 90.07% 99.92% 100.38% 99.85% 100.75% 99.94%
>
> * Tmpfs
> ** write
> 5M 121.85% 99.69% 131.57% 219.22% 99.85% 135.30%
> 60M 140.82% 99.70% 139.57% 98.14% 54.51% 73.65%
> 300M 97.99% 99.54% 99.60% 99.29% 99.57% 99.32%
> 2G 99.37% 99.62% 99.64% 98.72% 99.92% 99.18%
>
> ** read
> 5M 85.44% 92.96% 88.92% 129.13% 101.54% 97.87%
> 60M 64.41% 94.35% 88.10% 97.41% 95.75% 96.31%
> 300M 116.89% 106.52% 120.84% 132.17% 104.39% 130.63%
> 2G 86.27% 99.96% 87.47% 60.69% 99.44% 98.49%
I have played with the patch below but it didn't show too much
difference in the end or we end up doing even worse.
Here is the no_patch/patched comparison:
comparison (page reclaim is 100%)
* ext3 avg max min median
** Write
5M 81.49% 77.53% 101.91% 76.60%
60M 98.60% 95.58% 101.40% 99.62%
300M 101.68% 102.05% 101.19% 101.73%
2G 102.20% 102.25% 102.12% 102.22%
** Read
5M 103.94% 105.14% 103.95% 103.32%
60M 105.26% 107.91% 103.15% 104.95%
300M 104.83% 107.86% 101.65% 104.88%
2G 102.67% 101.26% 102.83% 103.35%
* Tmpfs
** Write
5M 107.68% 119.66% 105.26% 102.78%
60M 122.16% 138.51% 103.62% 121.09%
300M 101.03% 100.67% 101.11% 101.17%
2G 101.82% 101.66% 101.87% 101.87%
** Read
5M 102.47% 124.02% 98.05% 92.57%
60M 103.62% 121.03% 96.97% 96.52%
300M 98.90% 118.92% 102.64% 86.19%
2G 83.50% 76.34% 97.36% 81.92%
I am not sure it really makes sense to play with the priority here. All
the values we would end up with would be just wild guesses or mostly
artificial workloads. So I think it makes some to go with the original
version of the PageReclaim patch without any further fiddling with the
priority.
Is this sufficient to go with the patch or do people still have concerns
which would block the patch from merging?
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7cccd81..a240bdf 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -726,7 +726,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* writeback from reclaim and there is nothing else to
* reclaim.
*/
- if (PageReclaim(page)
+ if (PageReclaim(page) && sc->priority < DEF_PRIORITY - 3
&& may_enter_fs && !global_reclaim(sc))
wait_on_page_writeback(page);
else {
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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