Minchan Kim <minchan@xxxxxxxxxx> writes: > On Mon, Sep 25, 2017 at 01:54:42PM +0800, Huang, Ying wrote: >> Hi, Minchan, >> >> Minchan Kim <minchan@xxxxxxxxxx> writes: >> >> > Hi Huang, >> > >> > On Thu, Sep 21, 2017 at 09:33:10AM +0800, Huang, Ying wrote: >> >> From: Huang Ying <ying.huang@xxxxxxxxx> >> >> [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? The difference is, vma_ra_eanble: 0 => use original physical swap readahead vma_ra_enable: 1 && vma_ra_max_order: 0 => use VMA based swap readahead and disable the readahead. Best Regards, Huang, Ying -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
