On Mon, Sep 25, 2017 at 01:54:42PM +0800, Huang, Ying wrote: > Hi, Minchan, > > Minchan Kim <[email protected]> writes: > > > Hi Huang, > > > > On Thu, Sep 21, 2017 at 09:33:10AM +0800, Huang, Ying wrote: > >> From: Huang Ying <[email protected]> > > [snip] > > >> diff --git a/mm/Kconfig b/mm/Kconfig > >> index 9c4bdddd80c2..e62c8e2e34ef 100644 > >> --- a/mm/Kconfig > >> +++ b/mm/Kconfig > >> @@ -434,6 +434,26 @@ config THP_SWAP > >> > >> For selection by architectures with reasonable THP sizes. > >> > >> +config VMA_SWAP_READAHEAD > >> + bool "VMA based swap readahead" > >> + depends on SWAP > >> + default y > >> + help > >> + VMA based swap readahead detects page accessing pattern in a > >> + VMA and adjust the swap readahead window for pages in the > >> + VMA accordingly. It works better for more complex workload > >> + compared with the original physical swap readahead. > >> + > >> + It can be controlled via the following sysfs interface, > >> + > >> + /sys/kernel/mm/swap/vma_ra_enabled > >> + /sys/kernel/mm/swap/vma_ra_max_order > > > > It might be better to discuss in other thread but if you mention new > > interface here again, I will discuss it here. > > > > We are creating new ABI in here so I want to ask question in here. > > > > Did you consier to use /sys/block/xxx/queue/read_ahead_kb for the > > swap readahead knob? Reusing such common/consistent knob would be better > > than adding new separate konb. > > The problem is that the configuration of VMA based swap readahead is > global instead of block device specific. And because it works in > virtual way, that is, the swap blocks on the different block devices may > be readahead together. It's a little hard to use the block device > specific configuration.
Fair enough. page-cluster from the beginning should have been like that instead of vma_ra_max_order. One more questions: Do we need separate vma_ra_enable? Can't we disable it via echo 0 > /sys/kernel/mm/swap/vma_ra_max_order like page-cluster?
