Just another ping to have your comments. Thanks in advance!! On 6/7/2021 4:08 PM, Charan Teja Kalla wrote: > A gentle ping. > > --Charan > > On 5/31/2021 4:24 PM, Charan Teja Reddy wrote: >> The proactive compaction[1] gets triggered for every 500msec and run >> compaction on the node for COMPACTION_HPAGE_ORDER (usually order-9) >> pages based on the value set to sysctl.compaction_proactiveness. >> Triggering the compaction for every 500msec in search of >> COMPACTION_HPAGE_ORDER pages is not needed for all applications, >> especially on the embedded system usecases which may have few MB's of >> RAM. Enabling the proactive compaction in its state will endup in >> running almost always on such systems. >> >> Other side, proactive compaction can still be very much useful for >> getting a set of higher order pages in some controllable >> manner(controlled by using the sysctl.compaction_proactiveness). Thus on >> systems where enabling the proactive compaction always may proove not >> required, can trigger the same from user space on write to its sysctl >> interface. As an example, say app launcher decide to launch the memory >> heavy application which can be launched fast if it gets more higher >> order pages thus launcher can prepare the system in advance by >> triggering the proactive compaction from userspace. >> >> This triggering of proactive compaction is done on a write to >> sysctl.compaction_proactiveness by user. >> >> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=facdaa917c4d5a376d09d25865f5a863f906234a >> >> Signed-off-by: Charan Teja Reddy <charante@xxxxxxxxxxxxxx> >> --- >> changes in V2: >> - https://lore.kernel.org/patchwork/patch/1431283/ >> >> changes in V1: >> - https://lore.kernel.org/lkml/1619098678-8501-1-git-send-email-charante@xxxxxxxxxxxxxx/ >> >> Documentation/admin-guide/sysctl/vm.rst | 3 ++- >> include/linux/compaction.h | 2 ++ >> include/linux/mmzone.h | 1 + >> kernel/sysctl.c | 2 +- >> mm/compaction.c | 44 ++++++++++++++++++++++++++++++--- >> 5 files changed, 47 insertions(+), 5 deletions(-) >> >> diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst >> index 586cd4b..5e8097d 100644 >> --- a/Documentation/admin-guide/sysctl/vm.rst >> +++ b/Documentation/admin-guide/sysctl/vm.rst >> @@ -126,7 +126,8 @@ compaction_proactiveness >> >> This tunable takes a value in the range [0, 100] with a default value of >> 20. This tunable determines how aggressively compaction is done in the >> -background. Setting it to 0 disables proactive compaction. >> +background. On write of non zero value to this tunable will immediately >> +trigger the proactive compaction. Setting it to 0 disables proactive compaction. >> >> Note that compaction has a non-trivial system-wide impact as pages >> belonging to different processes are moved around, which could also lead >> diff --git a/include/linux/compaction.h b/include/linux/compaction.h >> index 4221888..04d5d9f 100644 >> --- a/include/linux/compaction.h >> +++ b/include/linux/compaction.h >> @@ -84,6 +84,8 @@ static inline unsigned long compact_gap(unsigned int order) >> extern unsigned int sysctl_compaction_proactiveness; >> extern int sysctl_compaction_handler(struct ctl_table *table, int write, >> void *buffer, size_t *length, loff_t *ppos); >> +extern int compaction_proactiveness_sysctl_handler(struct ctl_table *table, >> + int write, void *buffer, size_t *length, loff_t *ppos); >> extern int sysctl_extfrag_threshold; >> extern int sysctl_compact_unevictable_allowed; >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index 0d53eba..9455809 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -815,6 +815,7 @@ typedef struct pglist_data { >> enum zone_type kcompactd_highest_zoneidx; >> wait_queue_head_t kcompactd_wait; >> struct task_struct *kcompactd; >> + bool proactive_compact_trigger; >> #endif >> /* >> * This is a per-node reserve of pages that are not available >> diff --git a/kernel/sysctl.c b/kernel/sysctl.c >> index 14edf84..bed2fad 100644 >> --- a/kernel/sysctl.c >> +++ b/kernel/sysctl.c >> @@ -2840,7 +2840,7 @@ static struct ctl_table vm_table[] = { >> .data = &sysctl_compaction_proactiveness, >> .maxlen = sizeof(sysctl_compaction_proactiveness), >> .mode = 0644, >> - .proc_handler = proc_dointvec_minmax, >> + .proc_handler = compaction_proactiveness_sysctl_handler, >> .extra1 = SYSCTL_ZERO, >> .extra2 = &one_hundred, >> }, >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 84fde27..197e203 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -2708,6 +2708,30 @@ static void compact_nodes(void) >> */ >> unsigned int __read_mostly sysctl_compaction_proactiveness = 20; >> >> +int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write, >> + void *buffer, size_t *length, loff_t *ppos) >> +{ >> + int rc, nid; >> + >> + rc = proc_dointvec_minmax(table, write, buffer, length, ppos); >> + if (rc) >> + return rc; >> + >> + if (write && sysctl_compaction_proactiveness) { >> + for_each_online_node(nid) { >> + pg_data_t *pgdat = NODE_DATA(nid); >> + >> + if (pgdat->proactive_compact_trigger) >> + continue; >> + >> + pgdat->proactive_compact_trigger = true; >> + wake_up_interruptible(&pgdat->kcompactd_wait); >> + } >> + } >> + >> + return 0; >> +} >> + >> /* >> * This is the entry point for compacting all nodes via >> * /proc/sys/vm/compact_memory >> @@ -2752,7 +2776,8 @@ void compaction_unregister_node(struct node *node) >> >> static inline bool kcompactd_work_requested(pg_data_t *pgdat) >> { >> - return pgdat->kcompactd_max_order > 0 || kthread_should_stop(); >> + return pgdat->kcompactd_max_order > 0 || kthread_should_stop() || >> + pgdat->proactive_compact_trigger; >> } >> >> static bool kcompactd_node_suitable(pg_data_t *pgdat) >> @@ -2905,7 +2930,8 @@ static int kcompactd(void *p) >> trace_mm_compaction_kcompactd_sleep(pgdat->node_id); >> if (wait_event_freezable_timeout(pgdat->kcompactd_wait, >> kcompactd_work_requested(pgdat), >> - msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC))) { >> + msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC)) && >> + !pgdat->proactive_compact_trigger) { >> >> psi_memstall_enter(&pflags); >> kcompactd_do_work(pgdat); >> @@ -2917,10 +2943,20 @@ static int kcompactd(void *p) >> if (should_proactive_compact_node(pgdat)) { >> unsigned int prev_score, score; >> >> - if (proactive_defer) { >> + /* >> + * On wakeup of proactive compaction by sysctl >> + * write, ignore the accumulated defer score. >> + * Anyway, if the proactive compaction didn't >> + * make any progress for the new value, it will >> + * be further deferred by 2^COMPACT_MAX_DEFER_SHIFT >> + * times. >> + */ >> + if (proactive_defer && >> + !pgdat->proactive_compact_trigger) { >> proactive_defer--; >> continue; >> } >> + >> prev_score = fragmentation_score_node(pgdat); >> proactive_compact_node(pgdat); >> score = fragmentation_score_node(pgdat); >> @@ -2931,6 +2967,8 @@ static int kcompactd(void *p) >> proactive_defer = score < prev_score ? >> 0 : 1 << COMPACT_MAX_DEFER_SHIFT; >> } >> + if (pgdat->proactive_compact_trigger) >> + pgdat->proactive_compact_trigger = false; >> } >> >> return 0; >> > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
