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delayacct: track delays from write-protect copy

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Delay accounting does not track the delay of write-protect copy.  When
tasks trigger many write-protect copys(include COW and unsharing of
anonymous pages[1]), it may spend a amount of time waiting for them.  To
get the delay of tasks in write-protect copy, could help users to evaluate
the impact of using KSM or fork() or GUP.

Also update tools/accounting/getdelays.c:

    / # ./getdelays -dl -p 231
    print delayacct stats ON
    listen forever
    PID     231

    CPU             count     real total  virtual total    delay total  delay average
                     6247     1859000000     2154070021     1674255063          0.268ms
    IO              count    delay total  delay average
                        0              0              0ms
    SWAP            count    delay total  delay average
                        0              0              0ms
    RECLAIM         count    delay total  delay average
                        0              0              0ms
    THRASHING       count    delay total  delay average
                        0              0              0ms
    COMPACT         count    delay total  delay average
                        3          72758              0ms
    WPCOPY          count    delay total  delay average
                     3635      271567604              0ms

[1] commit 31cc5bc4af70("mm: support GUP-triggered unsharing of anonymous pages")

Link: https://lkml.kernel.org/r/20220409014342.2505532-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: wangyong <wang.yong12@zte.com.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yang Yang 2022-06-01 15:55:25 -07:00 • committed by akpm
parent 54eb8462f2
commit 662ce1dc9c
7 changed files with 76 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

28
include/linux/delayacct.h
View file

@ -45,9 +45,13 @@ struct task_delay_info {
u64 compact_start;
u64 compact_delay; /* wait for memory compact */
u64 wpcopy_start;
u64 wpcopy_delay; /* wait for write-protect copy */
u32 freepages_count; /* total count of memory reclaim */
u32 thrashing_count; /* total count of thrash waits */
u32 compact_count; /* total count of memory compact */
u32 wpcopy_count; /* total count of write-protect copy */
};
#endif
@ -75,6 +79,8 @@ extern void __delayacct_swapin_start(void);
extern void __delayacct_swapin_end(void);
extern void __delayacct_compact_start(void);
extern void __delayacct_compact_end(void);
extern void __delayacct_wpcopy_start(void);
extern void __delayacct_wpcopy_end(void);
static inline void delayacct_tsk_init(struct task_struct *tsk)
{
@ -191,6 +197,24 @@ static inline void delayacct_compact_end(void)
__delayacct_compact_end();
}
static inline void delayacct_wpcopy_start(void)
{
if (!static_branch_unlikely(&delayacct_key))
return;
if (current->delays)
__delayacct_wpcopy_start();
}
static inline void delayacct_wpcopy_end(void)
{
if (!static_branch_unlikely(&delayacct_key))
return;
if (current->delays)
__delayacct_wpcopy_end();
}
#else
static inline void delayacct_init(void)
{}
@ -225,6 +249,10 @@ static inline void delayacct_compact_start(void)
{}
static inline void delayacct_compact_end(void)
{}
static inline void delayacct_wpcopy_start(void)
{}
static inline void delayacct_wpcopy_end(void)
{}
#endif /* CONFIG_TASK_DELAY_ACCT */