Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Fri, Jun 01, 2018 at 03:26:04PM +0800, Aaron Lu wrote:
> On Mon, May 28, 2018 at 07:40:19PM +0800, kernel test robot wrote:
> >
> > Greeting,
> >
> > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > commit:
> >
> >
> > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > implement memory.swap.events")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> >
> > in testcase: vm-scalability
> > on test machine: 144 threads Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz with
> > 512G memory
> > with following parameters:
> >
> > runtime: 300s
> > size: 1T
> > test: lru-shm
> > cpufreq_governor: performance
> >
> > test-description: The motivation behind this suite is to exercise functions
> > and regions of the mm/ of the Linux kernel which are of interest to us.
> > test-url:
> > https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
> >
>
> With the patch I just sent out:
> "mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the
> same cacheline"
>
> Applying this commit on top doesn't yield 23% improvement any more, but
> a 6% performace drop...
> I found the culprit being the following one line introduced in this commit:
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index d90b0201a8c4..07ab974c0a49 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6019,13 +6019,17 @@ int mem_cgroup_try_charge_swap(struct page *page,
> swp_entry_t entry)
> if (!memcg)
> return 0;
>
> - if (!entry.val)
> + if (!entry.val) {
> + memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
Removing this line restored performance but it really doesn't make any
sense. Ying suggested it might be code alignment related and suggested
to use a different compiler than gcc-7.2. Then I used gcc-6.4 and turned
out the test result to be pretty much the same for the two commits:
(each test has run for 3 times)
$ grep throughput base/*/stats.json
base/0/stats.json: "vm-scalability.throughput": 89207489,
base/1/stats.json: "vm-scalability.throughput": 89982933,
base/2/stats.json: "vm-scalability.throughput": 90436592,
$ grep throughput head/*/stats.json
head/0/stats.json: "vm-scalability.throughput": 90882775,
head/1/stats.json: "vm-scalability.throughput": 90675220,
head/2/stats.json: "vm-scalability.throughput": 91173479,
So probably it's really related to code alignment and this bisected
commit doesn't cause performance change(as expected).
> return 0;
> + }
>
> memcg = mem_cgroup_id_get_online(memcg);
>
> If I remove that memcg_memory_event() call, performance will restore.
>
> It's beyond my understanding why this code path matters since there is
> no swap device setup in the test machine so I don't see how possible
> get_swap_page() could ever be called.
>
> Still investigating...
>
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Fri, Jun 01, 2018 at 03:26:04PM +0800, Aaron Lu wrote:
> On Mon, May 28, 2018 at 07:40:19PM +0800, kernel test robot wrote:
> >
> > Greeting,
> >
> > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > commit:
> >
> >
> > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > implement memory.swap.events")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> >
> > in testcase: vm-scalability
> > on test machine: 144 threads Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz with
> > 512G memory
> > with following parameters:
> >
> > runtime: 300s
> > size: 1T
> > test: lru-shm
> > cpufreq_governor: performance
> >
> > test-description: The motivation behind this suite is to exercise functions
> > and regions of the mm/ of the Linux kernel which are of interest to us.
> > test-url:
> > https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
> >
>
> With the patch I just sent out:
> "mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the
> same cacheline"
>
> Applying this commit on top doesn't yield 23% improvement any more, but
> a 6% performace drop...
> I found the culprit being the following one line introduced in this commit:
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index d90b0201a8c4..07ab974c0a49 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6019,13 +6019,17 @@ int mem_cgroup_try_charge_swap(struct page *page,
> swp_entry_t entry)
> if (!memcg)
> return 0;
>
> - if (!entry.val)
> + if (!entry.val) {
> + memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
Removing this line restored performance but it really doesn't make any
sense. Ying suggested it might be code alignment related and suggested
to use a different compiler than gcc-7.2. Then I used gcc-6.4 and turned
out the test result to be pretty much the same for the two commits:
(each test has run for 3 times)
$ grep throughput base/*/stats.json
base/0/stats.json: "vm-scalability.throughput": 89207489,
base/1/stats.json: "vm-scalability.throughput": 89982933,
base/2/stats.json: "vm-scalability.throughput": 90436592,
$ grep throughput head/*/stats.json
head/0/stats.json: "vm-scalability.throughput": 90882775,
head/1/stats.json: "vm-scalability.throughput": 90675220,
head/2/stats.json: "vm-scalability.throughput": 91173479,
So probably it's really related to code alignment and this bisected
commit doesn't cause performance change(as expected).
> return 0;
> + }
>
> memcg = mem_cgroup_id_get_online(memcg);
>
> If I remove that memcg_memory_event() call, performance will restore.
>
> It's beyond my understanding why this code path matters since there is
> no swap device setup in the test machine so I don't see how possible
> get_swap_page() could ever be called.
>
> Still investigating...
>
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Mon, May 28, 2018 at 07:40:19PM +0800, kernel test robot wrote:
>
> Greeting,
>
> FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> commit:
>
>
> commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol: implement
> memory.swap.events")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: vm-scalability
> on test machine: 144 threads Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz with
> 512G memory
> with following parameters:
>
> runtime: 300s
> size: 1T
> test: lru-shm
> cpufreq_governor: performance
>
> test-description: The motivation behind this suite is to exercise functions
> and regions of the mm/ of the Linux kernel which are of interest to us.
> test-url: https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
>
With the patch I just sent out:
"mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the
same cacheline"
Applying this commit on top doesn't yield 23% improvement any more, but
a 6% performace drop...
I found the culprit being the following one line introduced in this commit:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d90b0201a8c4..07ab974c0a49 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6019,13 +6019,17 @@ int mem_cgroup_try_charge_swap(struct page *page,
swp_entry_t entry)
if (!memcg)
return 0;
- if (!entry.val)
+ if (!entry.val) {
+ memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
return 0;
+ }
memcg = mem_cgroup_id_get_online(memcg);
If I remove that memcg_memory_event() call, performance will restore.
It's beyond my understanding why this code path matters since there is
no swap device setup in the test machine so I don't see how possible
get_swap_page() could ever be called.
Still investigating...
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Mon, May 28, 2018 at 07:40:19PM +0800, kernel test robot wrote:
>
> Greeting,
>
> FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> commit:
>
>
> commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol: implement
> memory.swap.events")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: vm-scalability
> on test machine: 144 threads Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz with
> 512G memory
> with following parameters:
>
> runtime: 300s
> size: 1T
> test: lru-shm
> cpufreq_governor: performance
>
> test-description: The motivation behind this suite is to exercise functions
> and regions of the mm/ of the Linux kernel which are of interest to us.
> test-url: https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
>
With the patch I just sent out:
"mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the
same cacheline"
Applying this commit on top doesn't yield 23% improvement any more, but
a 6% performace drop...
I found the culprit being the following one line introduced in this commit:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d90b0201a8c4..07ab974c0a49 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6019,13 +6019,17 @@ int mem_cgroup_try_charge_swap(struct page *page,
swp_entry_t entry)
if (!memcg)
return 0;
- if (!entry.val)
+ if (!entry.val) {
+ memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
return 0;
+ }
memcg = mem_cgroup_id_get_online(memcg);
If I remove that memcg_memory_event() call, performance will restore.
It's beyond my understanding why this code path matters since there is
no swap device setup in the test machine so I don't see how possible
get_swap_page() could ever be called.
Still investigating...
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue, May 29, 2018 at 10:27:51AM +0200, Michal Hocko wrote:
> On Tue 29-05-18 16:11:27, Aaron Lu wrote:
> > On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> > > On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > > > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > > > >
> > > > > > Greeting,
> > > > > >
> > > > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput
> > > > > > due to commit:
> > > > > >
> > > > > >
> > > > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > > > implement memory.swap.events")
> > > > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git
> > > > > > master
> > > > >
> > > > > This doesn't make any sense to me. The patch merely adds an
> > > > > accounting.
> > > > > It doesn't optimize anything. So I strongly suspect the result is just
> > > > > misleading or the test (environment) misconfigured. Not the first time
> > > > > I am seeing something like that I am afraid.
> > > > >
> > > >
> > > > Most likely the same situation as:
> > > > "
> > > > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > > > due to commit:
> > > >
> > > >
> > > > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > > > memory.events is uptodate when waking pollers")
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > > "
> > > >
> > > > Where the performance change is due to layout change of
> > > > 'struct mem_cgroup':
> > > > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
> > >
> > > I do not follow. How can _this_ patch lead to an improvement when it
> > > actually _adds_ an accounting? The other report you are mentioning is a
> >
> > This patch also changed the layout of 'struct mem_cgroup':
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index d99b71bc2c66..517096c3cc99 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -208,6 +210,9 @@ struct mem_cgroup {
> > atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
> > struct cgroup_file events_file;
> >
> > + /* handle for "memory.swap.events" */
> > + struct cgroup_file swap_events_file;
> > +
> > /* protect arrays of thresholds */
> > struct mutex thresholds_lock;
> >
> > And I'm guessing that might be the cause.
>
> Ohh, you are right! Sorry, I've missed that part.
Never mind, I want to thank you for taking a look at these reports :-)
I just tried to move this newly added field to the bottom of the
structure(just above 'struct mem_cgroup_per_node *nodeinfo[0];'), and
performance dropped to 82665166, still much better than base but already
worse than this patch.
As you said in another email, this is really fragile.
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue, May 29, 2018 at 10:27:51AM +0200, Michal Hocko wrote:
> On Tue 29-05-18 16:11:27, Aaron Lu wrote:
> > On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> > > On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > > > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > > > >
> > > > > > Greeting,
> > > > > >
> > > > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput
> > > > > > due to commit:
> > > > > >
> > > > > >
> > > > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > > > implement memory.swap.events")
> > > > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git
> > > > > > master
> > > > >
> > > > > This doesn't make any sense to me. The patch merely adds an
> > > > > accounting.
> > > > > It doesn't optimize anything. So I strongly suspect the result is just
> > > > > misleading or the test (environment) misconfigured. Not the first time
> > > > > I am seeing something like that I am afraid.
> > > > >
> > > >
> > > > Most likely the same situation as:
> > > > "
> > > > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > > > due to commit:
> > > >
> > > >
> > > > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > > > memory.events is uptodate when waking pollers")
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > > "
> > > >
> > > > Where the performance change is due to layout change of
> > > > 'struct mem_cgroup':
> > > > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
> > >
> > > I do not follow. How can _this_ patch lead to an improvement when it
> > > actually _adds_ an accounting? The other report you are mentioning is a
> >
> > This patch also changed the layout of 'struct mem_cgroup':
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index d99b71bc2c66..517096c3cc99 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -208,6 +210,9 @@ struct mem_cgroup {
> > atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
> > struct cgroup_file events_file;
> >
> > + /* handle for "memory.swap.events" */
> > + struct cgroup_file swap_events_file;
> > +
> > /* protect arrays of thresholds */
> > struct mutex thresholds_lock;
> >
> > And I'm guessing that might be the cause.
>
> Ohh, you are right! Sorry, I've missed that part.
Never mind, I want to thank you for taking a look at these reports :-)
I just tried to move this newly added field to the bottom of the
structure(just above 'struct mem_cgroup_per_node *nodeinfo[0];'), and
performance dropped to 82665166, still much better than base but already
worse than this patch.
As you said in another email, this is really fragile.
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue 29-05-18 16:11:27, Aaron Lu wrote:
> On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> > On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > > >
> > > > > Greeting,
> > > > >
> > > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due
> > > > > to commit:
> > > > >
> > > > >
> > > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > > implement memory.swap.events")
> > > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git
> > > > > master
> > > >
> > > > This doesn't make any sense to me. The patch merely adds an accounting.
> > > > It doesn't optimize anything. So I strongly suspect the result is just
> > > > misleading or the test (environment) misconfigured. Not the first time
> > > > I am seeing something like that I am afraid.
> > > >
> > >
> > > Most likely the same situation as:
> > > "
> > > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > > due to commit:
> > >
> > >
> > > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > > memory.events is uptodate when waking pollers")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > "
> > >
> > > Where the performance change is due to layout change of
> > > 'struct mem_cgroup':
> > > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
> >
> > I do not follow. How can _this_ patch lead to an improvement when it
> > actually _adds_ an accounting? The other report you are mentioning is a
>
> This patch also changed the layout of 'struct mem_cgroup':
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d99b71bc2c66..517096c3cc99 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -208,6 +210,9 @@ struct mem_cgroup {
> atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
> struct cgroup_file events_file;
>
> + /* handle for "memory.swap.events" */
> + struct cgroup_file swap_events_file;
> +
> /* protect arrays of thresholds */
> struct mutex thresholds_lock;
>
> And I'm guessing that might be the cause.
Ohh, you are right! Sorry, I've missed that part.
--
Michal Hocko
SUSE Labs
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue 29-05-18 16:11:27, Aaron Lu wrote:
> On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> > On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > > >
> > > > > Greeting,
> > > > >
> > > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due
> > > > > to commit:
> > > > >
> > > > >
> > > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > > implement memory.swap.events")
> > > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git
> > > > > master
> > > >
> > > > This doesn't make any sense to me. The patch merely adds an accounting.
> > > > It doesn't optimize anything. So I strongly suspect the result is just
> > > > misleading or the test (environment) misconfigured. Not the first time
> > > > I am seeing something like that I am afraid.
> > > >
> > >
> > > Most likely the same situation as:
> > > "
> > > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > > due to commit:
> > >
> > >
> > > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > > memory.events is uptodate when waking pollers")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > "
> > >
> > > Where the performance change is due to layout change of
> > > 'struct mem_cgroup':
> > > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
> >
> > I do not follow. How can _this_ patch lead to an improvement when it
> > actually _adds_ an accounting? The other report you are mentioning is a
>
> This patch also changed the layout of 'struct mem_cgroup':
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d99b71bc2c66..517096c3cc99 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -208,6 +210,9 @@ struct mem_cgroup {
> atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
> struct cgroup_file events_file;
>
> + /* handle for "memory.swap.events" */
> + struct cgroup_file swap_events_file;
> +
> /* protect arrays of thresholds */
> struct mutex thresholds_lock;
>
> And I'm guessing that might be the cause.
Ohh, you are right! Sorry, I've missed that part.
--
Michal Hocko
SUSE Labs
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > >
> > > > Greeting,
> > > >
> > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due
> > > > to commit:
> > > >
> > > >
> > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > implement memory.swap.events")
> > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > >
> > > This doesn't make any sense to me. The patch merely adds an accounting.
> > > It doesn't optimize anything. So I strongly suspect the result is just
> > > misleading or the test (environment) misconfigured. Not the first time
> > > I am seeing something like that I am afraid.
> > >
> >
> > Most likely the same situation as:
> > "
> > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > due to commit:
> >
> >
> > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > memory.events is uptodate when waking pollers")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > "
> >
> > Where the performance change is due to layout change of
> > 'struct mem_cgroup':
> > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
>
> I do not follow. How can _this_ patch lead to an improvement when it
> actually _adds_ an accounting? The other report you are mentioning is a
This patch also changed the layout of 'struct mem_cgroup':
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d99b71bc2c66..517096c3cc99 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -208,6 +210,9 @@ struct mem_cgroup {
atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
struct cgroup_file events_file;
+ /* handle for "memory.swap.events" */
+ struct cgroup_file swap_events_file;
+
/* protect arrays of thresholds */
struct mutex thresholds_lock;
And I'm guessing that might be the cause.
> _regression_ and I can imagine that the layout changes can lead to that
> result.
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> > On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > >
> > > > Greeting,
> > > >
> > > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due
> > > > to commit:
> > > >
> > > >
> > > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > > implement memory.swap.events")
> > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > >
> > > This doesn't make any sense to me. The patch merely adds an accounting.
> > > It doesn't optimize anything. So I strongly suspect the result is just
> > > misleading or the test (environment) misconfigured. Not the first time
> > > I am seeing something like that I am afraid.
> > >
> >
> > Most likely the same situation as:
> > "
> > FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> > due to commit:
> >
> >
> > commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> > memory.events is uptodate when waking pollers")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > "
> >
> > Where the performance change is due to layout change of
> > 'struct mem_cgroup':
> > http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
>
> I do not follow. How can _this_ patch lead to an improvement when it
> actually _adds_ an accounting? The other report you are mentioning is a
This patch also changed the layout of 'struct mem_cgroup':
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d99b71bc2c66..517096c3cc99 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -208,6 +210,9 @@ struct mem_cgroup {
atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
struct cgroup_file events_file;
+ /* handle for "memory.swap.events" */
+ struct cgroup_file swap_events_file;
+
/* protect arrays of thresholds */
struct mutex thresholds_lock;
And I'm guessing that might be the cause.
> _regression_ and I can imagine that the layout changes can lead to that
> result.
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > >
> > > Greeting,
> > >
> > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > > commit:
> > >
> > >
> > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > implement memory.swap.events")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> >
> > This doesn't make any sense to me. The patch merely adds an accounting.
> > It doesn't optimize anything. So I strongly suspect the result is just
> > misleading or the test (environment) misconfigured. Not the first time
> > I am seeing something like that I am afraid.
> >
>
> Most likely the same situation as:
> "
> FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> due to commit:
>
>
> commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> memory.events is uptodate when waking pollers")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> "
>
> Where the performance change is due to layout change of
> 'struct mem_cgroup':
> http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
I do not follow. How can _this_ patch lead to an improvement when it
actually _adds_ an accounting? The other report you are mentioning is a
_regression_ and I can imagine that the layout changes can lead to that
result.
--
Michal Hocko
SUSE Labs
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > >
> > > Greeting,
> > >
> > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > > commit:
> > >
> > >
> > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > > implement memory.swap.events")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> >
> > This doesn't make any sense to me. The patch merely adds an accounting.
> > It doesn't optimize anything. So I strongly suspect the result is just
> > misleading or the test (environment) misconfigured. Not the first time
> > I am seeing something like that I am afraid.
> >
>
> Most likely the same situation as:
> "
> FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> due to commit:
>
>
> commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> memory.events is uptodate when waking pollers")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> "
>
> Where the performance change is due to layout change of
> 'struct mem_cgroup':
> http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
I do not follow. How can _this_ patch lead to an improvement when it
actually _adds_ an accounting? The other report you are mentioning is a
_regression_ and I can imagine that the layout changes can lead to that
result.
--
Michal Hocko
SUSE Labs
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> On Mon 28-05-18 19:40:19, kernel test robot wrote:
> >
> > Greeting,
> >
> > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > commit:
> >
> >
> > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > implement memory.swap.events")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> This doesn't make any sense to me. The patch merely adds an accounting.
> It doesn't optimize anything. So I strongly suspect the result is just
> misleading or the test (environment) misconfigured. Not the first time
> I am seeing something like that I am afraid.
>
Most likely the same situation as:
"
FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
due to commit:
commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
memory.events is uptodate when waking pollers")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
"
Where the performance change is due to layout change of
'struct mem_cgroup':
http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> On Mon 28-05-18 19:40:19, kernel test robot wrote:
> >
> > Greeting,
> >
> > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to
> > commit:
> >
> >
> > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol:
> > implement memory.swap.events")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> This doesn't make any sense to me. The patch merely adds an accounting.
> It doesn't optimize anything. So I strongly suspect the result is just
> misleading or the test (environment) misconfigured. Not the first time
> I am seeing something like that I am afraid.
>
Most likely the same situation as:
"
FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
due to commit:
commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
memory.events is uptodate when waking pollers")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
"
Where the performance change is due to layout change of
'struct mem_cgroup':
http://lkml.kernel.org/r/20180528085201.ga2...@intel.com
