Messages in this thread Patch in this message | | | Date | Mon, 07 Apr 2014 11:37:55 -0700 | From | John Stultz <> | Subject | Re: [PATCH 2/5] vrange: Add purged page detection on setting memory non-volatile |
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On 03/23/2014 10:42 AM, KOSAKI Motohiro wrote: > On Fri, Mar 21, 2014 at 2:17 PM, John Stultz <john.stultz@linaro.org> wrote: >> Users of volatile ranges will need to know if memory was discarded. >> This patch adds the purged state tracking required to inform userland >> when it marks memory as non-volatile that some memory in that range >> was purged and needs to be regenerated. >> >> This simplified implementation which uses some of the logic from >> Minchan's earlier efforts, so credit to Minchan for his work. >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Android Kernel Team <kernel-team@android.com> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> Cc: Robert Love <rlove@google.com> >> Cc: Mel Gorman <mel@csn.ul.ie> >> Cc: Hugh Dickins <hughd@google.com> >> Cc: Dave Hansen <dave@sr71.net> >> Cc: Rik van Riel <riel@redhat.com> >> Cc: Dmitry Adamushko <dmitry.adamushko@gmail.com> >> Cc: Neil Brown <neilb@suse.de> >> Cc: Andrea Arcangeli <aarcange@redhat.com> >> Cc: Mike Hommey <mh@glandium.org> >> Cc: Taras Glek <tglek@mozilla.com> >> Cc: Jan Kara <jack@suse.cz> >> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> >> Cc: Michel Lespinasse <walken@google.com> >> Cc: Minchan Kim <minchan@kernel.org> >> Cc: linux-mm@kvack.org <linux-mm@kvack.org> >> Signed-off-by: John Stultz <john.stultz@linaro.org> >> --- >> include/linux/swap.h | 15 ++++++++-- >> include/linux/swapops.h | 10 +++++++ >> include/linux/vrange.h | 3 ++ >> mm/vrange.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 101 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/swap.h b/include/linux/swap.h >> index 46ba0c6..18c12f9 100644 >> --- a/include/linux/swap.h >> +++ b/include/linux/swap.h >> @@ -70,8 +70,19 @@ static inline int current_is_kswapd(void) >> #define SWP_HWPOISON_NUM 0 >> #endif >> >> -#define MAX_SWAPFILES \ >> - ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM) >> + >> +/* >> + * Purged volatile range pages >> + */ >> +#define SWP_VRANGE_PURGED_NUM 1 >> +#define SWP_VRANGE_PURGED (MAX_SWAPFILES + SWP_HWPOISON_NUM + SWP_MIGRATION_NUM) >> + >> + >> +#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) \ >> + - SWP_MIGRATION_NUM \ >> + - SWP_HWPOISON_NUM \ >> + - SWP_VRANGE_PURGED_NUM \ >> + ) > This change hwpoison and migration tag number. maybe ok, maybe not.
Though depending on config can't these tag numbers change anyway?
> I'd suggest to use younger number than hwpoison. > (That's why hwpoison uses younger number than migration)
So I can, but the way these are defined makes the results seem pretty terrible:
#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM \ + SWP_MVOLATILE_PURGED_NUM + 1)
Particularly when: #define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) \ - SWP_MIGRATION_NUM \ - SWP_HWPOISON_NUM \ - SWP_MVOLATILE_PURGED_NUM \ )
Its a lot of unnecessary mental gymnastics. Yuck.
Would a general cleanup like the following be ok to try to make this more extensible?
thanks -john
diff --git a/include/linux/swap.h b/include/linux/swap.h index 3507115..21387df 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -49,29 +49,38 @@ static inline int current_is_kswapd(void) * actions on faults. */ +enum { + /* + * NOTE: We use the high bits here (subtracting from + * 1<<MAX_SWPFILES_SHIFT), so to preserve the values insert + * new entries here at the top of the enum, not at the bottom + */ +#ifdef CONFIG_MEMORY_FAILURE + SWP_HWPOISON_NR, +#endif +#ifdef CONFIG_MIGRATION + SWP_MIGRATION_READ_NR, + SWP_MIGRATION_WRITE_NR, +#endif + SWP_MAX_NR, +}; +#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) - SWP_MAX_NR) + /* * NUMA node memory migration support */ #ifdef CONFIG_MIGRATION -#define SWP_MIGRATION_NUM 2 -#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM) -#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1) -#else -#define SWP_MIGRATION_NUM 0 +#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_MIGRATION_READ_NR) +#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_MIGRATION_WRITE_NR) #endif /* * Handling of hardware poisoned pages with memory corruption. */ #ifdef CONFIG_MEMORY_FAILURE -#define SWP_HWPOISON_NUM 1 -#define SWP_HWPOISON MAX_SWAPFILES -#else -#define SWP_HWPOISON_NUM 0 +#define SWP_HWPOISON (MAX_SWAPFILES + SWP_HWPOISON_NR) #endif -#define MAX_SWAPFILES \ - ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM) /* * Magic header for a swap area. The first part of the union is
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