| Message ID | 20230630092203.16080-1-andrew.yang@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fs: drop_caches: draining pages before dropping caches | expand |
Really more suitable for -mm to review. On Fri, Jun 30, 2023 at 05:22:02PM +0800, Andrew Yang wrote: > We expect a file page access after dropping caches should be a major > fault, but sometimes it's still a minor fault. That's because a file > page can't be dropped if it's in a per-cpu pagevec. Draining all pages > from per-cpu pagevec to lru list before trying to drop caches. > > Signed-off-by: Andrew Yang <andrew.yang@mediatek.com> > --- > fs/drop_caches.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/drop_caches.c b/fs/drop_caches.c > index e619c31b6bd9..b9575957a7c2 100644 > --- a/fs/drop_caches.c > +++ b/fs/drop_caches.c > @@ -10,6 +10,7 @@ > #include <linux/writeback.h> > #include <linux/sysctl.h> > #include <linux/gfp.h> > +#include <linux/swap.h> > #include "internal.h" > > /* A global variable is a bit ugly, but it keeps the code simple */ > @@ -59,6 +60,7 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write, > static int stfu; > > if (sysctl_drop_caches & 1) { > + lru_add_drain_all(); > iterate_supers(drop_pagecache_sb, NULL); > count_vm_event(DROP_PAGECACHE); > } > -- > 2.18.0 >
On Fri, 30 Jun 2023 17:22:02 +0800 Andrew Yang <andrew.yang@mediatek.com> wrote: > We expect a file page access after dropping caches should be a major > fault, but sometimes it's still a minor fault. That's because a file > page can't be dropped if it's in a per-cpu pagevec. Draining all pages > from per-cpu pagevec to lru list before trying to drop caches. > > --- a/fs/drop_caches.c > +++ b/fs/drop_caches.c > @@ -10,6 +10,7 @@ > #include <linux/writeback.h> > #include <linux/sysctl.h> > #include <linux/gfp.h> > +#include <linux/swap.h> > #include "internal.h" > > /* A global variable is a bit ugly, but it keeps the code simple */ > @@ -59,6 +60,7 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write, > static int stfu; > > if (sysctl_drop_caches & 1) { > + lru_add_drain_all(); > iterate_supers(drop_pagecache_sb, NULL); > count_vm_event(DROP_PAGECACHE); > } um, yes. I'm suprised that this oversight has survived 20+ years.
diff --git a/fs/drop_caches.c b/fs/drop_caches.c index e619c31b6bd9..b9575957a7c2 100644 --- a/fs/drop_caches.c +++ b/fs/drop_caches.c @@ -10,6 +10,7 @@ #include <linux/writeback.h> #include <linux/sysctl.h> #include <linux/gfp.h> +#include <linux/swap.h> #include "internal.h" /* A global variable is a bit ugly, but it keeps the code simple */ @@ -59,6 +60,7 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write, static int stfu; if (sysctl_drop_caches & 1) { + lru_add_drain_all(); iterate_supers(drop_pagecache_sb, NULL); count_vm_event(DROP_PAGECACHE); }
We expect a file page access after dropping caches should be a major fault, but sometimes it's still a minor fault. That's because a file page can't be dropped if it's in a per-cpu pagevec. Draining all pages from per-cpu pagevec to lru list before trying to drop caches. Signed-off-by: Andrew Yang <andrew.yang@mediatek.com> --- fs/drop_caches.c | 2 ++ 1 file changed, 2 insertions(+)