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Date: Fri, 13 Aug 2021 21:43:47 +0800
From: Hu Haowen <src.res@...il.cn>
To: yongw.pur@...il.com, tj@...nel.org, corbet@....net,
akpm@...ux-foundation.org, mhocko@...nel.org,
vdavydov.dev@...il.com, tglx@...utronix.de, peterz@...radead.org,
shakeelb@...gle.com, guro@...com, alexs@...nel.org,
richard.weiyang@...il.com, sh_def@....com, sfr@...b.auug.org.au,
wang.yong12@....com.cn, cgroups@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, yang.yang29@....com.cn
Subject: Re: [PATCH v1] mm: Add configuration to control whether vmpressure
notifier is enabled
在 2021/8/13 下午7:57, yongw.pur@...il.com 写道:
> From: wangyong <wang.yong12@....com.cn>
>
> Inspired by PSI features, vmpressure inotifier function should also be
> configured to decide whether it is used, because it is an independent
> feature which notifies the user of memory pressure.
>
> Since the vmpressure interface is used in kernel common code, for
> users who do not use the vmpressure function, there will be
> additional overhead.
>
> So we add configuration to control whether vmpressure notifier is
> enabled, and provide a boot parameter to use use vmpressure notifier
> flexibly
>
> Signed-off-by: wangyong <wang.yong12@....com.cn>
> ---
> Documentation/admin-guide/cgroup-v1/memory.rst | 3 ++-
> Documentation/admin-guide/kernel-parameters.txt | 3 +++
> include/linux/memcontrol.h | 2 ++
> include/linux/vmpressure.h | 7 +++++--
> init/Kconfig | 20 +++++++++++++++++++
> mm/Makefile | 3 ++-
> mm/memcontrol.c | 7 ++++++-
> mm/vmpressure.c | 26 +++++++++++++++++++++++++
> 8 files changed, 66 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
> index 41191b5..967418a 100644
> --- a/Documentation/admin-guide/cgroup-v1/memory.rst
> +++ b/Documentation/admin-guide/cgroup-v1/memory.rst
> @@ -388,6 +388,7 @@ a. Enable CONFIG_CGROUPS
> b. Enable CONFIG_MEMCG
> c. Enable CONFIG_MEMCG_SWAP (to use swap extension)
> d. Enable CONFIG_MEMCG_KMEM (to use kmem extension)
> +e. Enable CONFIG_MEMCG_VMPRESSURE (to use vmpressure extension)
>
> 3.1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?)
> -------------------------------------------------------------------
> @@ -855,7 +856,7 @@ At reading, current status of OOM is shown.
> The number of processes belonging to this cgroup killed by any
> kind of OOM killer.
>
> -11. Memory Pressure
> +11. Memory Pressure (CONFIG_MEMCG_VMPRESSURE)
> ===================
>
Please replace:
11. Memory Pressure (CONFIG_MEMCG_VMPRESSURE)
===================
with:
11. Memory Pressure (CONFIG_MEMCG_VMPRESSURE)
=============================================
Cheers,
Hu Haowen
> The pressure level notifications can be used to monitor the memory
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 4042a82..d119fb8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -6158,6 +6158,9 @@
> vmpoff= [KNL,S390] Perform z/VM CP command after power off.
> Format: <command>
>
> + vmpressure= [KNL] Enable or disable vmpressure notifier.
> + Format: <bool>
> +
> vsyscall= [X86-64]
> Controls the behavior of vsyscalls (i.e. calls to
> fixed addresses of 0xffffffffff600x00 from legacy
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 0ff1464..b201d8e 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -257,8 +257,10 @@ struct mem_cgroup {
>
> unsigned long soft_limit;
>
> +#ifdef CONFIG_MEMCG_VMPRESSURE
> /* vmpressure notifications */
> struct vmpressure vmpressure;
> +#endif
>
> /*
> * Should the OOM killer kill all belonging tasks, had it kill one?
> diff --git a/include/linux/vmpressure.h b/include/linux/vmpressure.h
> index 6a2f51e..dcae02e 100644
> --- a/include/linux/vmpressure.h
> +++ b/include/linux/vmpressure.h
> @@ -29,7 +29,8 @@ struct vmpressure {
>
> struct mem_cgroup;
>
> -#ifdef CONFIG_MEMCG
> +#ifdef CONFIG_MEMCG_VMPRESSURE
> +extern bool vmpressure_enable;
> extern void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
> unsigned long scanned, unsigned long reclaimed);
> extern void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio);
> @@ -48,5 +49,7 @@ static inline void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
> unsigned long scanned, unsigned long reclaimed) {}
> static inline void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg,
> int prio) {}
> -#endif /* CONFIG_MEMCG */
> +static inline void vmpressure_init(struct vmpressure *vmpr) {}
> +static inline void vmpressure_cleanup(struct vmpressure *vmpr) {}
> +#endif /* CONFIG_MEMCG_PRESSURE */
> #endif /* __LINUX_VMPRESSURE_H */
> diff --git a/init/Kconfig b/init/Kconfig
> index 71a028d..d3afeb2 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -948,6 +948,26 @@ config MEMCG_KMEM
> depends on MEMCG && !SLOB
> default y
>
> +config MEMCG_VMPRESSURE
> + bool "Memory pressure notifier"
> + depends on MEMCG
> + default y
> + help
> + Vmpressure extension is used to monitor the memory allocation cost.
> + The pressure level can be set according to the use scenario and
> + application will be notified through eventfd when memory pressure is at
> + the specific level (or higher).
> +
> +config VMPRESSURE_DEFAULT_DISABLED
> + bool "Require boot parameter to enable memory pressure notifier"
> + depends on MEMCG_VMPRESSURE
> + default n
> + help
> + If set, memory pressure notifier will be disabled but can be
> + enabled through passing vmpressure=1 on the kernel commandline
> + during boot.
> + For those who want to use memory pressure notifier flexibly.
> +
> config BLK_CGROUP
> bool "IO controller"
> depends on BLOCK
> diff --git a/mm/Makefile b/mm/Makefile
> index 970604e..e4f99c1 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -92,7 +92,8 @@ obj-$(CONFIG_MEMTEST) += memtest.o
> obj-$(CONFIG_MIGRATION) += migrate.o
> obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o
> obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
> -obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
> +obj-$(CONFIG_MEMCG) += memcontrol.o
> +obj-$(CONFIG_MEMCG_VMPRESSURE) += vmpressure.o
> obj-$(CONFIG_MEMCG_SWAP) += swap_cgroup.o
> obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
> obj-$(CONFIG_GUP_TEST) += gup_test.o
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 3e7c205..ee060ae2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -248,6 +248,7 @@ static inline bool should_force_charge(void)
> (current->flags & PF_EXITING);
> }
>
> +#ifdef CONFIG_MEMCG_VMPRESSURE
> /* Some nice accessors for the vmpressure. */
> struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
> {
> @@ -260,6 +261,7 @@ struct mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr)
> {
> return container_of(vmpr, struct mem_cgroup, vmpressure);
> }
> +#endif
>
> #ifdef CONFIG_MEMCG_KMEM
> extern spinlock_t css_set_lock;
> @@ -4794,9 +4796,12 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
> } else if (!strcmp(name, "memory.oom_control")) {
> event->register_event = mem_cgroup_oom_register_event;
> event->unregister_event = mem_cgroup_oom_unregister_event;
> - } else if (!strcmp(name, "memory.pressure_level")) {
> +#ifdef CONFIG_MEMCG_VMPRESSURE
> + } else if (vmpressure_enable &&
> + !strcmp(name, "memory.pressure_level")) {
> event->register_event = vmpressure_register_event;
> event->unregister_event = vmpressure_unregister_event;
> +#endif
> } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
> event->register_event = memsw_cgroup_usage_register_event;
> event->unregister_event = memsw_cgroup_usage_unregister_event;
> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
> index 76518e4..b0d4358 100644
> --- a/mm/vmpressure.c
> +++ b/mm/vmpressure.c
> @@ -67,6 +67,19 @@ static const unsigned int vmpressure_level_critical = 95;
> */
> static const unsigned int vmpressure_level_critical_prio = ilog2(100 / 10);
>
> +DEFINE_STATIC_KEY_FALSE(vmpressure_disabled);
> +#ifdef CONFIG_VMPRESSURE_DEFAULT_DISABLED
> +bool vmpressure_enable;
> +#else
> +bool vmpressure_enable = true;
> +#endif
> +static int __init setup_vmpressure(char *str)
> +{
> + return kstrtobool(str, &vmpressure_enable) == 0;
> +}
> +__setup("vmpressure=", setup_vmpressure);
> +
> +
> static struct vmpressure *work_to_vmpressure(struct work_struct *work)
> {
> return container_of(work, struct vmpressure, work);
> @@ -246,6 +259,9 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
>
> vmpr = memcg_to_vmpressure(memcg);
>
> + if (static_branch_likely(&vmpressure_disabled))
> + return;
> +
> /*
> * Here we only want to account pressure that userland is able to
> * help us with. For example, suppose that DMA zone is under
> @@ -326,6 +342,8 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
> */
> void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
> {
> + if (static_branch_likely(&vmpressure_disabled))
> + return;
> /*
> * We only use prio for accounting critical level. For more info
> * see comment for vmpressure_level_critical_prio variable above.
> @@ -450,6 +468,11 @@ void vmpressure_unregister_event(struct mem_cgroup *memcg,
> */
> void vmpressure_init(struct vmpressure *vmpr)
> {
> + if (!vmpressure_enable) {
> + static_branch_enable(&vmpressure_disabled);
> + return;
> + }
> +
> spin_lock_init(&vmpr->sr_lock);
> mutex_init(&vmpr->events_lock);
> INIT_LIST_HEAD(&vmpr->events);
> @@ -465,6 +488,9 @@ void vmpressure_init(struct vmpressure *vmpr)
> */
> void vmpressure_cleanup(struct vmpressure *vmpr)
> {
> +
> + if (static_branch_likely(&vmpressure_disabled))
> + return;
> /*
> * Make sure there is no pending work before eventfd infrastructure
> * goes away.
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