On Wed, Jun 01, 2011 at 09:05:18PM -0700, Ying Han wrote:

On Wed, Jun 1, 2011 at 4:52 PM, Hiroyuki Kamezawa
[off-list ref] wrote:

quoted

2011/6/1 Johannes Weiner [off-list ref]:

quoted

Hi,

this is the second version of the memcg naturalization series.  The
notable changes since the first submission are:

   o the hierarchy walk is now intermittent and will abort and
     remember the last scanned child after sc->nr_to_reclaim pages
     have been reclaimed during the walk in one zone (Rik)

   o the global lru lists are never scanned when memcg is enabled
     after #2 'memcg-aware global reclaim', which makes this patch
     self-sufficient and complete without requiring the per-memcg lru
     lists to be exclusive (Michal)

   o renamed sc->memcg and sc->current_memcg to sc->target_mem_cgroup
     and sc->mem_cgroup and fixed their documentation, I hope this is
     better understandable now (Rik)

   o the reclaim statistic counters have been renamed.  there is no
     more distinction between 'pgfree' and 'pgsteal', it is now
     'pgreclaim' in both cases; 'kswapd' has been replaced by
     'background'

   o fixed a nasty crash in the hierarchical soft limit check that
     happened during global reclaim in memcgs that are hierarchical
     but have no hierarchical parents themselves

   o properly implemented the memcg-aware unevictable page rescue
     scanner, there were several blatant bugs in there

   o documentation on new public interfaces

Thanks for your input on the first version.

I ran microbenchmarks (sparse file catting, essentially) to stress
reclaim and LRU operations.  There is no measurable overhead for
!CONFIG_MEMCG, memcg disabled during boot, memcg enabled but no
configured groups, and hard limit reclaim.

I also ran single-threaded kernbenchs in four unlimited memcgs in
parallel, contained in a hard-limited hierarchical parent that put
constant pressure on the workload.  There is no measurable difference
in runtime, the pgpgin/pgpgout counters, and fairness among memcgs in
this test compared to an unpatched kernel.  Needs more evaluation,
especially with a higher number of memcgs.

The soft limit changes are also proven to work in so far that it is
possible to prioritize between children in a hierarchy under pressure
and that runtime differences corresponded directly to the soft limit
settings in the previously described kernbench setup with staggered
soft limits on the groups, but this needs quantification.

Based on v2.6.39.

Hmm, I welcome and will review this patches but.....some points I want to say.

1. No more conflict with Ying's work ?
   Could you explain what she has and what you don't in this v2 ?
   If Ying's one has something good to be merged to your set, please
include it.

My patch I sent out last time was doing rework of soft_limit reclaim.
It convert the RB-tree based to
a linked list round-robin fashion of all memcgs across their soft
limit per-zone.

I will apply this patch and try to test it. After that i will get
better idea whether or not it is being covered here.

Thanks!!

quoted

4. This work can be splitted into some small works.
    a) fix for current code and clean ups

quoted

    a') statistics

quoted

    b) soft limit rework

quoted

    c) change global reclaim

My last patchset starts with a patch reverting the RB-tree
implementation of the soft_limit
reclaim, and then the new round-robin implementation comes on the
following patches.

I like the ordering here, and that is consistent w/ the plan we
discussed earlier in LSF. Changing
the global reclaim would be the last step when the changes before that
have been well understood
and tested.

Sorry If that is how it is done here. I will read through the patchset.

It's not.  The way I implemented soft limits depends on global reclaim
performing hierarchical reclaim.  I don't see how I can reverse the
order with this dependency.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>