FYI, we noticed the below changes on
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
commit b72fd1470c9735f53485d089aa918dc327a86077 ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines")
test case: lkp-st02/dd-write/5m-11HDD-JBOD-cfq-xfs-10dd
e28c951ff01a805 b72fd1470c9735f53485d089a
--------------- -------------------------
1.06 ~ 6% -41.7% 0.62 ~ 3% TOTAL perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page
1.34 ~ 2% -19.8% 1.07 ~ 2% TOTAL perf-profile.cpu-cycles.__block_write_begin.xfs_vm_write_begin.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
1.19 ~ 5% -12.1% 1.05 ~ 4% TOTAL perf-profile.cpu-cycles.copy_from_user_atomic_iovec.iov_iter_copy_from_user_atomic.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
2.78 ~ 1% -16.3% 2.32 ~ 4% TOTAL perf-profile.cpu-cycles.__clear_user.read_zero.read_zero.vfs_read.sys_read
2.96e+09 ~ 4% -5.2% 2.806e+09 ~ 0% TOTAL perf-stat.cache-misses
3.86e+12 ~ 5% -5.2% 3.658e+12 ~ 1% TOTAL perf-stat.ref-cycles
Legend:
~XX% - stddev percent
[+-]XX% - change percent
Disclaimer:
Results have been estimated based on internal Intel analysis and are provided
for informational purposes only. Any difference in system hardware or software
design or configuration may affect actual performance.
Thanks,
Aaron
On Thu, Jul 31, 2014 at 01:50:35PM +0800, Aaron Lu wrote:
> FYI, we noticed the below changes on
>
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> commit b72fd1470c9735f53485d089aa918dc327a86077 ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines")
>
> test case: lkp-st02/dd-write/5m-11HDD-JBOD-cfq-xfs-10dd
>
> e28c951ff01a805 b72fd1470c9735f53485d089a
> --------------- -------------------------
> 1.06 ~ 6% -41.7% 0.62 ~ 3% TOTAL perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page
> 1.34 ~ 2% -19.8% 1.07 ~ 2% TOTAL perf-profile.cpu-cycles.__block_write_begin.xfs_vm_write_begin.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> 1.19 ~ 5% -12.1% 1.05 ~ 4% TOTAL perf-profile.cpu-cycles.copy_from_user_atomic_iovec.iov_iter_copy_from_user_atomic.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> 2.78 ~ 1% -16.3% 2.32 ~ 4% TOTAL perf-profile.cpu-cycles.__clear_user.read_zero.read_zero.vfs_read.sys_read
> 2.96e+09 ~ 4% -5.2% 2.806e+09 ~ 0% TOTAL perf-stat.cache-misses
> 3.86e+12 ~ 5% -5.2% 3.658e+12 ~ 1% TOTAL perf-stat.ref-cycles
>
> Legend:
> ~XX% - stddev percent
> [+-]XX% - change percent
>
I'm not exactly sure what I'm reading here. I think it is reporting on cpu
cycles and cache misses used in various kernel functions. It's not clear what
the units are but it looks like percentages of overall cycles spent in the
reported functions. That may or may not be good depending on whether there
is a higher cost elsewhere pushing the percentages down but that detail
is not in the report. It looks like this is reporting that fewer clock
cycles are being spent and incurring fewer cache misses. What is the problem?
--
Mel Gorman
SUSE Labs
On Thu, Jul 31, 2014 at 09:48:32AM +0100, Mel Gorman wrote:
> On Thu, Jul 31, 2014 at 01:50:35PM +0800, Aaron Lu wrote:
> > FYI, we noticed the below changes on
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > commit b72fd1470c9735f53485d089aa918dc327a86077 ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines")
> >
> > test case: lkp-st02/dd-write/5m-11HDD-JBOD-cfq-xfs-10dd
> >
> > e28c951ff01a805 b72fd1470c9735f53485d089a
> > --------------- -------------------------
> > 1.06 ~ 6% -41.7% 0.62 ~ 3% TOTAL perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page
> > 1.34 ~ 2% -19.8% 1.07 ~ 2% TOTAL perf-profile.cpu-cycles.__block_write_begin.xfs_vm_write_begin.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> > 1.19 ~ 5% -12.1% 1.05 ~ 4% TOTAL perf-profile.cpu-cycles.copy_from_user_atomic_iovec.iov_iter_copy_from_user_atomic.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> > 2.78 ~ 1% -16.3% 2.32 ~ 4% TOTAL perf-profile.cpu-cycles.__clear_user.read_zero.read_zero.vfs_read.sys_read
> > 2.96e+09 ~ 4% -5.2% 2.806e+09 ~ 0% TOTAL perf-stat.cache-misses
> > 3.86e+12 ~ 5% -5.2% 3.658e+12 ~ 1% TOTAL perf-stat.ref-cycles
> >
> > Legend:
> > ~XX% - stddev percent
> > [+-]XX% - change percent
> >
>
> I'm not exactly sure what I'm reading here. I think it is reporting on cpu
> cycles and cache misses used in various kernel functions. It's not clear what
> the units are but it looks like percentages of overall cycles spent in the
> reported functions. That may or may not be good depending on whether there
> is a higher cost elsewhere pushing the percentages down but that detail
> is not in the report. It looks like this is reporting that fewer clock
> cycles are being spent and incurring fewer cache misses. What is the problem?
LKP does not report problems only, it will also report commits that make
things better :-)
>From the perf-stat.cache-misses, I think it is indicating your commit
does something for good.
Thanks,
Aaron
On Thu, Jul 31, 2014 at 05:01:30PM +0800, Aaron Lu wrote:
> On Thu, Jul 31, 2014 at 09:48:32AM +0100, Mel Gorman wrote:
> > On Thu, Jul 31, 2014 at 01:50:35PM +0800, Aaron Lu wrote:
> > > FYI, we noticed the below changes on
> > >
> > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > > commit b72fd1470c9735f53485d089aa918dc327a86077 ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines")
> > >
> > > test case: lkp-st02/dd-write/5m-11HDD-JBOD-cfq-xfs-10dd
> > >
> > > e28c951ff01a805 b72fd1470c9735f53485d089a
> > > --------------- -------------------------
> > > 1.06 ~ 6% -41.7% 0.62 ~ 3% TOTAL perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page
> > > 1.34 ~ 2% -19.8% 1.07 ~ 2% TOTAL perf-profile.cpu-cycles.__block_write_begin.xfs_vm_write_begin.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> > > 1.19 ~ 5% -12.1% 1.05 ~ 4% TOTAL perf-profile.cpu-cycles.copy_from_user_atomic_iovec.iov_iter_copy_from_user_atomic.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter
> > > 2.78 ~ 1% -16.3% 2.32 ~ 4% TOTAL perf-profile.cpu-cycles.__clear_user.read_zero.read_zero.vfs_read.sys_read
> > > 2.96e+09 ~ 4% -5.2% 2.806e+09 ~ 0% TOTAL perf-stat.cache-misses
> > > 3.86e+12 ~ 5% -5.2% 3.658e+12 ~ 1% TOTAL perf-stat.ref-cycles
> > >
> > > Legend:
> > > ~XX% - stddev percent
> > > [+-]XX% - change percent
> > >
> >
> > I'm not exactly sure what I'm reading here. I think it is reporting on cpu
> > cycles and cache misses used in various kernel functions. It's not clear what
> > the units are but it looks like percentages of overall cycles spent in the
> > reported functions. That may or may not be good depending on whether there
> > is a higher cost elsewhere pushing the percentages down but that detail
> > is not in the report. It looks like this is reporting that fewer clock
> > cycles are being spent and incurring fewer cache misses. What is the problem?
>
> LKP does not report problems only, it will also report commits that make
> things better :-)
>
> From the perf-stat.cache-misses, I think it is indicating your commit
> does something for good.
>
Hooray! Thanks for the good news :D
--
Mel Gorman
SUSE Labs