Re: Memory pressure handling with iSCSI

From: Badari Pulavarty
Date: Tue Jul 26 2005 - 13:49:43 EST


On Tue, 2005-07-26 at 11:11 -0700, Andrew Morton wrote:
> Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:
> >
> > After KS & OLS discussions about memory pressure, I wanted to re-do
> > iSCSI testing with "dd"s to see if we are throttling writes.
> >
> > I created 50 10-GB ext3 filesystems on iSCSI luns. Test is simple
> > 50 dds (one per filesystem). System seems to throttle memory properly
> > and making progress. (Machine doesn't respond very well for anything
> > else, but my vmstat keeps running - 100% sys time).
>
> It's important to monitor /proc/meminfo too - the amount of dirty/writeback
> pages, etc.
>
> btw, 100% system time is quite appalling. Are you sure vmstat is telling
> the truth? If so, where's it all being spent?
>
>

Well, profile doesn't show any time in "default_idle". So
I believe, vmstat is telling the truth.

# cat /proc/meminfo
MemTotal: 7143628 kB
MemFree: 43252 kB
Buffers: 16736 kB
Cached: 6683348 kB
SwapCached: 5336 kB
Active: 14460 kB
Inactive: 6686928 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 7143628 kB
LowFree: 43252 kB
SwapTotal: 1048784 kB
SwapFree: 1017920 kB
Dirty: 6225664 kB
Writeback: 447272 kB
Mapped: 10460 kB
Slab: 362136 kB
CommitLimit: 4620596 kB
Committed_AS: 168616 kB
PageTables: 2452 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 9888 kB
VmallocChunk: 34359728447 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 2048 kB



# echo 2 > /proc/profile; sleep 5; readprofile -
m /usr/src/*12.3/System.map | sort -nr
1634737 total 0.5464
1468569 shrink_zone 390.5769
21203 unlock_page 331.2969
19497 release_pages 46.8678
19061 __wake_up_bit 397.1042
17936 page_referenced 53.3810
10679 lru_add_drain 133.4875
7348 page_waitqueue 76.5417
5877 tg3_poll 2.4007
4650 cond_resched 41.5179
4476 copy_user_generic 15.0201
1973 do_get_write_access 1.2583
1858 __mod_page_state 38.7083
1754 tg3_start_xmit 0.9876
1348 journal_dirty_metadata 2.1063
1250 __find_get_block 2.7902
1224 journal_add_journal_head 2.6379
1082 kmem_cache_free 11.2708
1077 tcp_sendpage 0.3580
1076 tcp_ack 0.1431
1075 __make_request 0.7999
1035 tg3_interrupt_tagged 2.5875
1022 __pagevec_lru_add 4.5625
928 tcp_transmit_skb 0.4677
924 kmem_cache_alloc 14.4375
900 thread_return 3.5294
819 __ext3_get_inode_loc 0.9307
754 established_get_next 2.2440
711 journal_cancel_revoke 1.4335
684 file_send_actor 7.1250


Thanks,
Badari

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