| Message ID | 20210126003417.72B4BCFB@viggo.jf.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Migrate Pages in lieu of discard | expand |
On Mon, 25 Jan 2021, Dave Hansen wrote: > > From: Dave Hansen <dave.hansen@linux.intel.com> > > RECLAIM_ZONE was assumed to be unused because it was never explicitly > used in the kernel. However, there were a number of places where it > was checked implicitly by checking 'node_reclaim_mode' for a zero > value. > > These zero checks are not great because it is not obvious what a zero > mode *means* in the code. Replace them with a helper which makes it > more obvious: node_reclaim_enabled(). > > This helper also provides a handy place to explicitly check the > RECLAIM_ZONE bit itself. Check it explicitly there to make it more > obvious where the bit can affect behavior. > > This should have no functional impact. > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> > Acked-by: Christoph Lameter <cl@linux.com> > Cc: Alex Shi <alex.shi@linux.alibaba.com> > Cc: "Tobin C. Harding" <tobin@kernel.org> > Cc: Christoph Lameter <cl@linux.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Qian Cai <cai@lca.pw> > Cc: Daniel Wagner <dwagner@suse.de> > Cc: osalvador <osalvador@suse.de> Acked-by: David Rientjes <rientjes@google.com>
On Mon, Jan 25, 2021 at 04:34:17PM -0800, Dave Hansen wrote: > > From: Dave Hansen <dave.hansen@linux.intel.com> > > RECLAIM_ZONE was assumed to be unused because it was never explicitly > used in the kernel. However, there were a number of places where it > was checked implicitly by checking 'node_reclaim_mode' for a zero > value. > > These zero checks are not great because it is not obvious what a zero > mode *means* in the code. Replace them with a helper which makes it > more obvious: node_reclaim_enabled(). > > This helper also provides a handy place to explicitly check the > RECLAIM_ZONE bit itself. Check it explicitly there to make it more > obvious where the bit can affect behavior. > > This should have no functional impact. > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> > Acked-by: Christoph Lameter <cl@linux.com> > Cc: Alex Shi <alex.shi@linux.alibaba.com> > Cc: "Tobin C. Harding" <tobin@kernel.org> > Cc: Christoph Lameter <cl@linux.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Qian Cai <cai@lca.pw> > Cc: Daniel Wagner <dwagner@suse.de> > Cc: osalvador <osalvador@suse.de> Reviewed-by: Oscar Salvador <osalvador@suse.de>
diff -puN include/linux/swap.h~mm-vmscan-node_reclaim_mode_helper include/linux/swap.h --- a/include/linux/swap.h~mm-vmscan-node_reclaim_mode_helper 2021-01-25 16:23:08.330866712 -0800 +++ b/include/linux/swap.h 2021-01-25 16:23:08.339866712 -0800 @@ -12,6 +12,7 @@ #include <linux/fs.h> #include <linux/atomic.h> #include <linux/page-flags.h> +#include <uapi/linux/mempolicy.h> #include <asm/page.h> struct notifier_block; @@ -380,6 +381,12 @@ extern int sysctl_min_slab_ratio; #define node_reclaim_mode 0 #endif +static inline bool node_reclaim_enabled(void) +{ + /* Is any node_reclaim_mode bit set? */ + return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP); +} + extern void check_move_unevictable_pages(struct pagevec *pvec); extern int kswapd_run(int nid); diff -puN mm/khugepaged.c~mm-vmscan-node_reclaim_mode_helper mm/khugepaged.c --- a/mm/khugepaged.c~mm-vmscan-node_reclaim_mode_helper 2021-01-25 16:23:08.332866712 -0800 +++ b/mm/khugepaged.c 2021-01-25 16:23:08.340866712 -0800 @@ -797,7 +797,7 @@ static bool khugepaged_scan_abort(int ni * If node_reclaim_mode is disabled, then no extra effort is made to * allocate memory locally. */ - if (!node_reclaim_mode) + if (!node_reclaim_enabled()) return false; /* If there is a count for this node already, it must be acceptable */ diff -puN mm/page_alloc.c~mm-vmscan-node_reclaim_mode_helper mm/page_alloc.c --- a/mm/page_alloc.c~mm-vmscan-node_reclaim_mode_helper 2021-01-25 16:23:08.335866712 -0800 +++ b/mm/page_alloc.c 2021-01-25 16:23:08.342866712 -0800 @@ -3875,7 +3875,7 @@ retry: if (alloc_flags & ALLOC_NO_WATERMARKS) goto try_this_zone; - if (node_reclaim_mode == 0 || + if (!node_reclaim_enabled() || !zone_allows_reclaim(ac->preferred_zoneref->zone, zone)) continue;