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Groups > linux.kernel > #1486630
| From | Tim Chen <tim.c.chen@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out |
| Date | 2016-09-19 18:00 +0200 |
| Message-ID | <sj999-7ii-35@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <sgQ0W-6Y0-29@gated-at.bofh.it> <sgRJp-7Xu-43@gated-at.bofh.it> <sgS2J-8jW-15@gated-at.bofh.it> <sh5Mm-t4-11@gated-at.bofh.it> <sj11T-2o5-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, 2016-09-19 at 16:11 +0900, Minchan Kim wrote: > Hi Tim, > > On Tue, Sep 13, 2016 at 11:52:27PM +0000, Chen, Tim C wrote: > > > > > > > > > > > > > > > > > - Avoid CPU time for splitting, collapsing THP across swap out/in. > > > Yes, if you want, please give us how bad it is. > > > > > It could be pretty bad. In an experiment with THP turned on and we > > enter swap, 50% of the cpu are spent in the page compaction path. > It's page compaction overhead, especially, pageblock_pfn_to_page. > Why is it related to overhead THP split for swapout? > I don't understand. Today you have to split a large page into 4K pages to swap it out. Then after you swap in all the 4K pages, you have to re-compact them back into a large page. If you can swap the large page out as a contiguous unit, and swap it back in as a single large page, the splitting and re-compaction back into a large page can be avoided. Tim
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Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-09 22:40 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-13 08:20 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-13 08:50 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-13 09:10 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-13 11:00 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-13 11:20 +0200
RE: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Chen, Tim C" <tim.c.chen@intel.com> - 2016-09-14 02:00 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-19 09:20 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Tim Chen <tim.c.chen@linux.intel.com> - 2016-09-19 18:00 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-18 04:00 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-19 09:10 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-20 05:00 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out "Huang\, Ying" <ying.huang@intel.com> - 2016-09-20 07:30 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim <minchan@kernel.org> - 2016-09-20 07:40 +0200
Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Andrea Arcangeli <aarcange@redhat.com> - 2016-09-13 16:40 +0200
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