Minchan Kim <minchan@xxxxxxxxxx> writes: > On Tue, Oct 10, 2017 at 02:08:55PM +0800, Huang, Ying wrote: >> From: Huang Ying <ying.huang@xxxxxxxxx> >> >> When the VMA based swap readahead was introduced, a new knob >> >> /sys/kernel/mm/swap/vma_ra_max_order >> >> was added as the max window of VMA swap readahead. This is to make it >> possible to use different max window for VMA based readahead and >> original physical readahead. But Minchan Kim pointed out that this >> will cause a regression because setting page-cluster sysctl to zero >> cannot disable swap readahead with the change. >> >> To fix the regression, the page-cluster sysctl is used as the max >> window of both the VMA based swap readahead and original physical swap >> readahead. If more fine grained control is needed in the future, more >> knobs can be added as the subordinate knobs of the page-cluster >> sysctl. >> >> The vma_ra_max_order knob is deleted. Because the knob was >> introduced in v4.14-rc1, and this patch is targeting being merged >> before v4.14 releasing, there should be no existing users of this >> newly added ABI. >> >> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> >> Cc: Rik van Riel <riel@xxxxxxxxxx> >> Cc: Shaohua Li <shli@xxxxxxxxxx> >> Cc: Hugh Dickins <hughd@xxxxxxxxxx> >> Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx> >> Cc: Tim Chen <tim.c.chen@xxxxxxxxx> >> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> >> Reported-by: Minchan Kim <minchan@xxxxxxxxxx> > > It seems your script is Ccing only with Cc: tag, not other tags. > Fix it so any participant of topic can get the mail. I just used `git send-email`, no other scripts. We need to fix `git send-email`? >> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> >> --- >> Documentation/ABI/testing/sysfs-kernel-mm-swap | 10 --------- >> mm/swap_state.c | 31 ++------------------------ >> 2 files changed, 2 insertions(+), 39 deletions(-) >> >> diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-swap b/Documentation/ABI/testing/sysfs-kernel-mm-swap >> index 587db52084c7..94672016c268 100644 >> --- a/Documentation/ABI/testing/sysfs-kernel-mm-swap >> +++ b/Documentation/ABI/testing/sysfs-kernel-mm-swap >> @@ -14,13 +14,3 @@ Description: Enable/disable VMA based swap readahead. >> still used for tmpfs etc. other users. If set to >> false, the global swap readahead algorithm will be >> used for all swappable pages. >> - >> -What: /sys/kernel/mm/swap/vma_ra_max_order >> -Date: August 2017 >> -Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx> >> -Description: The max readahead size in order for VMA based swap readahead >> - >> - VMA based swap readahead algorithm will readahead at >> - most 1 << max_order pages for each readahead. The >> - real readahead size for each readahead will be scaled >> - according to the estimation algorithm. >> diff --git a/mm/swap_state.c b/mm/swap_state.c >> index ed91091d1e68..4d01ecff62d9 100644 >> --- a/mm/swap_state.c >> +++ b/mm/swap_state.c >> @@ -39,10 +39,6 @@ struct address_space *swapper_spaces[MAX_SWAPFILES]; >> static unsigned int nr_swapper_spaces[MAX_SWAPFILES]; >> bool swap_vma_readahead = true; >> >> -#define SWAP_RA_MAX_ORDER_DEFAULT 3 >> - >> -static int swap_ra_max_order = SWAP_RA_MAX_ORDER_DEFAULT; >> - >> #define SWAP_RA_WIN_SHIFT (PAGE_SHIFT / 2) >> #define SWAP_RA_HITS_MASK ((1UL << SWAP_RA_WIN_SHIFT) - 1) >> #define SWAP_RA_HITS_MAX SWAP_RA_HITS_MASK >> @@ -672,7 +668,8 @@ struct page *swap_readahead_detect(struct vm_fault *vmf, >> if (page) >> return page; >> >> - max_win = 1 << READ_ONCE(swap_ra_max_order); >> + max_win = 1 << min_t(unsigned int, READ_ONCE(page_cluster), >> + SWAP_RA_ORDER_CEILING); > > > Why doesn't you check it in swap_use_vma_readahead in my original patch? > My purpose in there is to avoid unnecessary function call and > lookup_swap_cache in there. > If you really want to do that in swap_readahead_detect itself, please > move above routine to ahead of faddr = vmf->address to avoid unncessary > instructions. Although the avoided instructions is just a few, I can move the max window checking as the first statements in the function. 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>
