Messages in this thread | | | Subject | Re: [LKP] Re: [mm] 8cc621d2f4: fio.write_iops -21.8% regression | From | "Xing, Zhengjun" <> | Date | Fri, 3 Sep 2021 15:11:33 +0800 |
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Hi Minchan,
Do you have time to look at this? I re-test it in v5.14, the regression still existed. Thanks.
On 5/26/2021 12:57 AM, Chris Goldsworthy wrote: > On 2021-05-25 09:39, Minchan Kim wrote: >> On Tue, May 25, 2021 at 08:16:03AM -0700, Minchan Kim wrote: >> >> < snip > >> >>> > > On Thu, May 20, 2021 at 04:31:44PM +0800, kernel test robot wrote: >>> > > > >>> > > > >>> > > > Greeting, >>> > > > >>> > > > FYI, we noticed a -21.8% regression of fio.write_iops due to >>> commit: >>> > > > >>> > > > >>> > > > commit: 8cc621d2f45ddd3dc664024a647ee7adf48d79a5 ("mm: fs: >>> > > > invalidate BH LRU during page migration") >>> > > > >>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master >>> > > > >>> > > > >>> > > > in testcase: fio-basic >>> > > > on test machine: 96 threads 2 sockets Intel(R) Xeon(R) Gold >>> 6252 CPU >>> > > > @ 2.10GHz with 256G memory >>> > > > with following parameters: >>> > > > >>> > > > disk: 2pmem >>> > > > fs: ext4 >>> > > > runtime: 200s >>> > > > nr_task: 50% >>> > > > time_based: tb >>> > > > rw: randwrite >>> > > > bs: 4k >>> > > > ioengine: libaio >>> > > > test_size: 200G >>> > > > cpufreq_governor: performance >>> > > > ucode: 0x5003006 >>> > > > >>> > > > test-description: Fio is a tool that will spawn a number of >>> threads >>> > > > or processes doing a particular type of I/O action as >>> specified by >>> > > > the user. >>> > > > test-url: https://github.com/axboe/fio >>> > > > >>> > > > >>> > > > >>> > > > If you fix the issue, kindly add following tag >>> > > > Reported-by: kernel test robot <oliver.sang@intel.com> >>> > > > >>> > > > >>> > > > Details are as below: >>> > > > >>> --------------------------------------------------------------------------------------------------> >>> > > > >>> > > > >>> > > > To reproduce: >>> > > > >>> > > > git clone https://github.com/intel/lkp-tests.git >>> > > > cd lkp-tests >>> > > > bin/lkp install job.yaml # job file is >>> > > > attached in this email >>> > > > bin/lkp split-job --compatible job.yaml # generate >>> the yaml >>> > > > file for lkp run >>> > > > bin/lkp run generated-yaml-file >>> > > >>> > > Hi, >>> > > >>> > > I tried to insall the lkp-test in my machine by following above >>> guide >>> > > but failed >>> > > due to package problems(I guess it's my problem since I use >>> something >>> > > particular >>> > > environement). However, I guess it comes from increased miss >>> ratio of >>> > > bh_lrus >>> > > since the patch caused more frequent invalidation of the bh_lrus >>> calls >>> > > compared >>> > > to old. For example, lru_add_drain could be called from several hot >>> > > places(e.g., >>> > > unmap and pagevec_release from several path) and it could keeps >>> > > invalidating >>> > > bh_lrus. >>> > > >>> > > IMO, we should move the overhead from such hot path to cold one. >>> How >>> > > about this? >>> > > >>> > > From ebf4ede1cf32fb14d85f0015a3693cb8e1b8dbfe Mon Sep 17 >>> 00:00:00 2001 >>> > > From: Minchan Kim <minchan@kernel.org> >>> > > Date: Thu, 20 May 2021 11:17:56 -0700 >>> > > Subject: [PATCH] invalidate bh_lrus only at lru_add_drain_all >>> > > >>> > > Not-Yet-Signed-off-by: Minchan Kim <minchan@kernel.org> >>> > > --- >>> > > mm/swap.c | 15 +++++++++++++-- >>> > > 1 file changed, 13 insertions(+), 2 deletions(-) >>> > > >>> > > diff --git a/mm/swap.c b/mm/swap.c >>> > > index dfb48cf9c2c9..d6168449e28c 100644 >>> > > --- a/mm/swap.c >>> > > +++ b/mm/swap.c >>> > > @@ -642,7 +642,6 @@ void lru_add_drain_cpu(int cpu) >>> > > pagevec_lru_move_fn(pvec, lru_lazyfree_fn); >>> > > >>> > > activate_page_drain(cpu); >>> > > - invalidate_bh_lrus_cpu(cpu); >>> > > } >>> > > >>> > > /** >>> > > @@ -725,6 +724,17 @@ void lru_add_drain(void) >>> > > local_unlock(&lru_pvecs.lock); >>> > > } >>> > > >>> > > +void lru_and_bh_lrus_drain(void) >>> > > +{ >>> > > + int cpu; >>> > > + >>> > > + local_lock(&lru_pvecs.lock); >>> > > + cpu = smp_processor_id(); >>> > > + lru_add_drain_cpu(cpu); >>> > > + local_unlock(&lru_pvecs.lock); >>> > > + invalidate_bh_lrus_cpu(cpu); >>> > > +} >>> > > + >>> > >>> > Nit: drop int cpu? >>> >>> Do you mean to suggest using smp_processor_id at both places >>> instead of local varaible? Since the invalidate_bh_lrus_cpu >>> is called out of the lru_pvecs.lock, I wanted to express >>> the draining happens at the same CPU via storing the CPU. >>> >>> > >>> > > void lru_add_drain_cpu_zone(struct zone *zone) >>> > > { >>> > > local_lock(&lru_pvecs.lock); >>> > > @@ -739,7 +749,7 @@ static DEFINE_PER_CPU(struct work_struct, >>> > > lru_add_drain_work); >>> > > >>> > > static void lru_add_drain_per_cpu(struct work_struct *dummy) >>> > > { >>> > > - lru_add_drain(); >>> > > + lru_and_bh_lrus_drain(); >>> > > } >>> > > >>> > > /* >>> > > @@ -881,6 +891,7 @@ void lru_cache_disable(void) >>> > > __lru_add_drain_all(true); >>> > > #else >>> > > lru_add_drain(); >>> > > + invalidate_bh_lrus_cpu(smp_processor_id()); >>> > > #endif >>> > > } >>> > >>> > Can't we replace the call to lru_add_drain() and >>> > invalidate_bh_lrus_cpu(smp_processor_id()) with a single call to >>> > lru_and_bh_lrus_drain()? >>> >>> Good idea. >> >> From 8caadeb49d82403a08643dfbdb0b7749017c00bb Mon Sep 17 00:00:00 2001 >> From: Minchan Kim <minchan@kernel.org> >> Date: Tue, 25 May 2021 08:19:17 -0700 >> Subject: [PATCH] mm: fs: invalidate bh_lrus for only cold path >> >> kernel test robot reported the regression of fio.write_iops[1] >> with [2]. >> >> Since lru_add_drain is called frequently, invalidate bh_lrus >> there could increase bh_lrus cache miss ratio, which needs >> more IO in the end. >> >> This patch moves the bh_lrus invalidation from the hot path( >> e.g., zap_page_range, pagevec_release) to cold path(i.e., >> lru_add_drain_all, lru_cache_disable). >> >> [1] >> https://lore.kernel.org/lkml/20210520083144.GD14190@xsang-OptiPlex-9020/ >> [2] 8cc621d2f45d, mm: fs: invalidate BH LRU during page migration >> Cc: Xing, Zhengjun <zhengjun.xing@intel.com> >> Cc: Chris Goldsworthy <cgoldswo@codeaurora.org> >> Reported-by: kernel test robot <oliver.sang@intel.com> >> Signed-off-by: Minchan Kim <minchan@kernel.org> >> --- >> mm/swap.c | 16 +++++++++++++--- >> 1 file changed, 13 insertions(+), 3 deletions(-) >> >> diff --git a/mm/swap.c b/mm/swap.c >> index 1958d5feb148..3e25d99a9dbb 100644 >> --- a/mm/swap.c >> +++ b/mm/swap.c >> @@ -642,7 +642,6 @@ void lru_add_drain_cpu(int cpu) >> pagevec_lru_move_fn(pvec, lru_lazyfree_fn); >> >> activate_page_drain(cpu); >> - invalidate_bh_lrus_cpu(cpu); >> } >> >> /** >> @@ -725,6 +724,17 @@ void lru_add_drain(void) >> local_unlock(&lru_pvecs.lock); >> } >> >> +static void lru_add_and_bh_lrus_drain(void) >> +{ >> + int cpu; >> + >> + local_lock(&lru_pvecs.lock); >> + cpu = smp_processor_id(); >> + lru_add_drain_cpu(cpu); >> + local_unlock(&lru_pvecs.lock); >> + invalidate_bh_lrus_cpu(cpu); >> +} >> + >> void lru_add_drain_cpu_zone(struct zone *zone) >> { >> local_lock(&lru_pvecs.lock); >> @@ -739,7 +749,7 @@ static DEFINE_PER_CPU(struct work_struct, >> lru_add_drain_work); >> >> static void lru_add_drain_per_cpu(struct work_struct *dummy) >> { >> - lru_add_drain(); >> + lru_add_and_bh_lrus_drain(); >> } >> >> /* >> @@ -880,7 +890,7 @@ void lru_cache_disable(void) >> */ >> __lru_add_drain_all(true); >> #else >> - lru_add_drain(); >> + lru_add_and_bh_lrus_drain(); >> #endif >> } > > Feel free to add: > Reviewed-by: Chris Goldsworthy <cgoldswo@codeaurora.org> >
-- Zhengjun Xing
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