Re: [RESEND PATCH v10 08/25] dept: Apply sdt_might_sleep_{start,end}() to PG_{locked,writeback} wait
On Mon, Aug 21, 2023 at 05:09:44AM +0100, Matthew Wilcox wrote:
> On Mon, Aug 21, 2023 at 12:46:20PM +0900, Byungchul Park wrote:
> > @@ -1219,6 +1220,9 @@ static inline bool folio_trylock_flag(struct folio
> > *folio, int bit_nr,
> > /* How many times do we accept lock stealing from under a waiter? */
> > int sysctl_page_lock_unfairness = 5;
> >
> > +static struct dept_map __maybe_unused PG_locked_map =
> > DEPT_MAP_INITIALIZER(PG_locked_map, NULL);
> > +static struct dept_map __maybe_unused PG_writeback_map =
> > DEPT_MAP_INITIALIZER(PG_writeback_map, NULL);
>
> Hmm, why are these "maybe unused"? *digs*. Ah. Because
> sdt_might_sleep_start() becomes a no-op macro if DEPT is disabled.
>
> OK, the right way to handle this is
>
> #ifdef CONFIG_DEPT
> #define DEPT_MAP(name)static struct dept_map name = \
> DEPT_MAP_INITIALIZER(name, NULL)
> #else
> #define DEPT_MAP(name)/* */
> #endif
>
> And now DEPT takes up no space if disabled.
Currently:
#if !defined(CONFIG_DEPT)
struct dept_map { };
#endif
So I think it doesn't take space at all. Do you think I still need to
introduce e.g. DEPT_MAP()? Then I will. Thank you!
Byungchul
> /* */; is a somewhat unusual thing to see, but since this must work at
> top level, we can't use "do { } while (0)" like we usually do. Given
> where else this is likely to be used, i don't think it's going to be
> a problem ...
Re: [RESEND PATCH v10 08/25] dept: Apply sdt_might_sleep_{start,end}() to PG_{locked,writeback} wait
On Mon, Aug 21, 2023 at 12:46:20PM +0900, Byungchul Park wrote:
> @@ -1219,6 +1220,9 @@ static inline bool folio_trylock_flag(struct folio
> *folio, int bit_nr,
> /* How many times do we accept lock stealing from under a waiter? */
> int sysctl_page_lock_unfairness = 5;
>
> +static struct dept_map __maybe_unused PG_locked_map =
> DEPT_MAP_INITIALIZER(PG_locked_map, NULL);
> +static struct dept_map __maybe_unused PG_writeback_map =
> DEPT_MAP_INITIALIZER(PG_writeback_map, NULL);
Hmm, why are these "maybe unused"? *digs*. Ah. Because
sdt_might_sleep_start() becomes a no-op macro if DEPT is disabled.
OK, the right way to handle this is
#ifdef CONFIG_DEPT
#define DEPT_MAP(name) static struct dept_map name = \
DEPT_MAP_INITIALIZER(name, NULL)
#else
#define DEPT_MAP(name) /* */
#endif
And now DEPT takes up no space if disabled.
/* */; is a somewhat unusual thing to see, but since this must work at
top level, we can't use "do { } while (0)" like we usually do. Given
where else this is likely to be used, i don't think it's going to be
a problem ...
[RESEND PATCH v10 08/25] dept: Apply sdt_might_sleep_{start, end}() to PG_{locked, writeback} wait
Makes Dept able to track dependencies by PG_{locked,writeback} waits.
Signed-off-by: Byungchul Park
---
mm/filemap.c | 11 +++
1 file changed, 11 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index 83dda76d1fc3..eed64dc88e43 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -44,6 +44,7 @@
#include
#include
#include
+#include
#include
#include
#include "internal.h"
@@ -1219,6 +1220,9 @@ static inline bool folio_trylock_flag(struct folio
*folio, int bit_nr,
/* How many times do we accept lock stealing from under a waiter? */
int sysctl_page_lock_unfairness = 5;
+static struct dept_map __maybe_unused PG_locked_map =
DEPT_MAP_INITIALIZER(PG_locked_map, NULL);
+static struct dept_map __maybe_unused PG_writeback_map =
DEPT_MAP_INITIALIZER(PG_writeback_map, NULL);
+
static inline int folio_wait_bit_common(struct folio *folio, int bit_nr,
int state, enum behavior behavior)
{
@@ -1230,6 +1234,11 @@ static inline int folio_wait_bit_common(struct folio
*folio, int bit_nr,
unsigned long pflags;
bool in_thrashing;
+ if (bit_nr == PG_locked)
+ sdt_might_sleep_start(_locked_map);
+ else if (bit_nr == PG_writeback)
+ sdt_might_sleep_start(_writeback_map);
+
if (bit_nr == PG_locked &&
!folio_test_uptodate(folio) && folio_test_workingset(folio)) {
delayacct_thrashing_start(_thrashing);
@@ -1331,6 +1340,8 @@ static inline int folio_wait_bit_common(struct folio
*folio, int bit_nr,
*/
finish_wait(q, wait);
+ sdt_might_sleep_end();
+
if (thrashing) {
delayacct_thrashing_end(_thrashing);
psi_memstall_leave();
--
2.17.1
