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Date:   Tue, 5 Jun 2018 09:38:35 -0700
From:   Daniel Jordan <daniel.m.jordan@oracle.com>
To:     "Huang, Ying" <ying.huang@intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm -V3 00/21] mm, THP, swap: Swapout/swapin THP in one
 piece
Message-ID: <20180605163835.72n52hlrxtbjalhg@ca-dmjordan1.us.oracle.com>
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 <20180604180642.qexvwe5dqvkgraij@ca-dmjordan1.us.oracle.com>
 <87lgbt3ley.fsf@yhuang-dev.intel.com>
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On Tue, Jun 05, 2018 at 12:30:13PM +0800, Huang, Ying wrote:
> Daniel Jordan <daniel.m.jordan@oracle.com> writes:
> 
> > On Wed, May 23, 2018 at 04:26:04PM +0800, Huang, Ying wrote:
> >> And for all, Any comment is welcome!
> >> 
> >> This patchset is based on the 2018-05-18 head of mmotm/master.
> >
> > Trying to review this and it doesn't apply to mmotm-2018-05-18-16-44.  git
> > fails on patch 10:
> >
> > Applying: mm, THP, swap: Support to count THP swapin and its fallback
> > error: Documentation/vm/transhuge.rst: does not exist in index
> > Patch failed at 0010 mm, THP, swap: Support to count THP swapin and its fallback
> >
> > Sure enough, this tag has Documentation/vm/transhuge.txt but not the .rst
> > version.  Was this the tag you meant?  If so did you pull in some of Mike
> > Rapoport's doc changes on top?
> 
> I use the mmotm tree at
> 
> git://git.cmpxchg.org/linux-mmotm.git
> 
> Maybe you are using the other one?

Yes I was, and I didn't know about this other tree, thanks!  Working my way
through your changes now.

> 
> >>             base                  optimized
> >> ---------------- -------------------------- 
> >>          %stddev     %change         %stddev
> >>              \          |                \  
> >>    1417897   2%    +992.8%   15494673        vm-scalability.throughput
> >>    1020489   4%   +1091.2%   12156349        vmstat.swap.si
> >>    1255093   3%    +940.3%   13056114        vmstat.swap.so
> >>    1259769   7%   +1818.3%   24166779        meminfo.AnonHugePages
> >>   28021761           -10.7%   25018848   2%  meminfo.AnonPages
> >>   64080064   4%     -95.6%    2787565  33%  interrupts.CAL:Function_call_interrupts
> >>      13.91   5%     -13.8        0.10  27%  perf-profile.children.cycles-pp.native_queued_spin_lock_slowpath
> >> 
> > ...snip...
> >> test, while in optimized kernel, that is 96.6%.  The TLB flushing IPI
> >> (represented as interrupts.CAL:Function_call_interrupts) reduced
> >> 95.6%, while cycles for spinlock reduced from 13.9% to 0.1%.  These
> >> are performance benefit of THP swapout/swapin too.
> >
> > Which spinlocks are we spending less time on?
> 
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irq.mem_cgroup_commit_charge.do_swap_page.__handle_mm_fault": 4.39,
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.free_pcppages_bulk.drain_pages_zone.drain_pages": 1.53,
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.get_page_from_freelist.__alloc_pages_slowpath.__alloc_pages_nodemask": 1.34,
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.swapcache_free_entries.free_swap_slot.do_swap_page": 1.02,
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irq.shrink_inactive_list.shrink_node_memcg.shrink_node": 0.61,
> "perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock_irq.shrink_active_list.shrink_node_memcg.shrink_node": 0.54,

Nice, seems like lru_lock followed by zone->lock are the main improvements.