* + memcg-introduce-per-memcg-reclaim-interface.patch added to -mm tree
@ 2022-04-22 21:37 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2022-04-22 21:37 UTC (permalink / raw)
To: mm-commits, yuzhao, yosryahmed, weixugc, vaibhav, tj, tim.c.chen,
shuah, schatzberg.dan, roman.gushchin, rientjes, mkoutny, mhocko,
lizefan.x, hannes, gthelen, dave.hansen, corbet, chenwandun,
shakeelb, akpm
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 9134 bytes --]
The patch titled
Subject: memcg: introduce per-memcg reclaim interface
has been added to the -mm tree. Its filename is
memcg-introduce-per-memcg-reclaim-interface.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@google.com>
Subject: memcg: introduce per-memcg reclaim interface
Patch series "memcg: introduce per-memcg proactive reclaim", v4.
Add a memory.reclaim proactive reclaim interface. The rationale behind
the interface and how it works are in the first patch.
This patch (of 4):
Introduce a memcg interface to trigger memory reclaim on a memory cgroup.
Use case: Proactive Reclaim
---------------------------
A userspace proactive reclaimer can continuously probe the memcg to
reclaim a small amount of memory. This gives more accurate and up-to-date
workingset estimation as the LRUs are continuously sorted and can
potentially provide more deterministic memory overcommit behavior. The
memory overcommit controller can provide more proactive response to the
changing behavior of the running applications instead of being reactive.
A userspace reclaimer's purpose in this case is not a complete replacement
for kswapd or direct reclaim, it is to proactively identify memory savings
opportunities and reclaim some amount of cold pages set by the policy to
free up the memory for more demanding jobs or scheduling new jobs.
A user space proactive reclaimer is used in Google data centers.
Additionally, Meta's TMO paper recently referenced a very similar
interface used for user space proactive reclaim:
https://dl.acm.org/doi/pdf/10.1145/3503222.3507731
Benefits of a user space reclaimer:
-----------------------------------
1) More flexible on who should be charged for the cpu of the memory
reclaim. For proactive reclaim, it makes more sense to be centralized.
2) More flexible on dedicating the resources (like cpu). The memory
overcommit controller can balance the cost between the cpu usage and
the memory reclaimed.
3) Provides a way to the applications to keep their LRUs sorted, so,
under memory pressure better reclaim candidates are selected. This
also gives more accurate and uptodate notion of working set for an
application.
Why memory.high is not enough?
------------------------------
- memory.high can be used to trigger reclaim in a memcg and can
potentially be used for proactive reclaim. However there is a big
downside in using memory.high. It can potentially introduce high
reclaim stalls in the target application as the allocations from the
processes or the threads of the application can hit the temporary
memory.high limit.
- Userspace proactive reclaimers usually use feedback loops to decide
how much memory to proactively reclaim from a workload. The metrics
used for this are usually either refaults or PSI, and these metrics will
become messy if the application gets throttled by hitting the high
limit.
- memory.high is a stateful interface, if the userspace proactive
reclaimer crashes for any reason while triggering reclaim it can leave
the application in a bad state.
- If a workload is rapidly expanding, setting memory.high to proactively
reclaim memory can result in actually reclaiming more memory than
intended.
The benefits of such interface and shortcomings of existing interface
were further discussed in this RFC thread:
https://lore.kernel.org/linux-mm/5df21376-7dd1-bf81-8414-32a73cea45dd@google.com/
Interface:
----------
Introduce a very simple memcg interface 'echo 10M > memory.reclaim' to
trigger reclaim in the target memory cgroup.
The interface is introduced as a nested-keyed file to allow for future
optional arguments to be easily added to configure the behavior of
reclaim.
Possible Extensions:
--------------------
- This interface can be extended with an additional parameter or flags
to allow specifying one or more types of memory to reclaim from (e.g.
file, anon, ..).
- The interface can also be extended with a node mask to reclaim from
specific nodes. This has use cases for reclaim-based demotion in memory
tiering systens.
- A similar per-node interface can also be added to support proactive
reclaim and reclaim-based demotion in systems without memcg.
- Add a timeout parameter to make it easier for user space to call the
interface without worrying about being blocked for an undefined amount
of time.
For now, let's keep things simple by adding the basic functionality.
[yosryahmed@google.com: refreshed to current master, updated commit message based on recent discussions and use cases]
Link: https://lkml.kernel.org/r/20220421234426.3494842-2-yosryahmed@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Wei Xu <weixugc@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/admin-guide/cgroup-v2.rst | 21 ++++++++++
mm/memcontrol.c | 44 ++++++++++++++++++++++
2 files changed, 65 insertions(+)
--- a/Documentation/admin-guide/cgroup-v2.rst~memcg-introduce-per-memcg-reclaim-interface
+++ a/Documentation/admin-guide/cgroup-v2.rst
@@ -1208,6 +1208,27 @@ PAGE_SIZE multiple when read back.
high limit is used and monitored properly, this limit's
utility is limited to providing the final safety net.
+ memory.reclaim
+ A write-only nested-keyed file which exists for all cgroups.
+
+ This is a simple interface to trigger memory reclaim in the
+ target cgroup.
+
+ This file accepts a single key, the number of bytes to reclaim.
+ No nested keys are currently supported.
+
+ Example::
+
+ echo "1G" > memory.reclaim
+
+ The interface can be later extended with nested keys to
+ configure the reclaim behavior. For example, specify the
+ type of memory to reclaim from (anon, file, ..).
+
+ Please note that the kernel can over or under reclaim from
+ the target cgroup. If less bytes are reclaimed than the
+ specified amount, -EAGAIN is returned.
+
memory.oom.group
A read-write single value file which exists on non-root
cgroups. The default value is "0".
--- a/mm/memcontrol.c~memcg-introduce-per-memcg-reclaim-interface
+++ a/mm/memcontrol.c
@@ -6356,6 +6356,45 @@ static ssize_t memory_oom_group_write(st
return nbytes;
}
+static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ unsigned int nr_retries = MAX_RECLAIM_RETRIES;
+ unsigned long nr_to_reclaim, nr_reclaimed = 0;
+ int err;
+
+ buf = strstrip(buf);
+ err = page_counter_memparse(buf, "", &nr_to_reclaim);
+ if (err)
+ return err;
+
+ while (nr_reclaimed < nr_to_reclaim) {
+ unsigned long reclaimed;
+
+ if (signal_pending(current))
+ return -EINTR;
+
+ /* This is the final attempt, drain percpu lru caches in the
+ * hope of introducing more evictable pages for
+ * try_to_free_mem_cgroup_pages().
+ */
+ if (!nr_retries)
+ lru_add_drain_all();
+
+ reclaimed = try_to_free_mem_cgroup_pages(memcg,
+ nr_to_reclaim - nr_reclaimed,
+ GFP_KERNEL, true);
+
+ if (!reclaimed && !nr_retries--)
+ return -EAGAIN;
+
+ nr_reclaimed += reclaimed;
+ }
+
+ return nbytes;
+}
+
static struct cftype memory_files[] = {
{
.name = "current",
@@ -6414,6 +6453,11 @@ static struct cftype memory_files[] = {
.seq_show = memory_oom_group_show,
.write = memory_oom_group_write,
},
+ {
+ .name = "reclaim",
+ .flags = CFTYPE_NS_DELEGATABLE,
+ .write = memory_reclaim,
+ },
{ } /* terminate */
};
_
Patches currently in -mm which might be from shakeelb@google.com are
memcg-introduce-per-memcg-reclaim-interface.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + memcg-introduce-per-memcg-reclaim-interface.patch added to -mm tree
@ 2022-04-25 20:18 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2022-04-25 20:18 UTC (permalink / raw)
To: mm-commits, yuzhao, yosryahmed, weixugc, vaibhav, tj, tim.c.chen,
shuah, roman.gushchin, rientjes, mkoutny, mhocko, lizefan.x,
hannes, gthelen, dave.hansen, corbet, chenwandun, shakeelb, akpm
The patch titled
Subject: memcg: introduce per-memcg reclaim interface
has been added to the -mm tree. Its filename is
memcg-introduce-per-memcg-reclaim-interface.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@google.com>
Subject: memcg: introduce per-memcg reclaim interface
This patch series adds a memory.reclaim proactive reclaim interface.
The rationale behind the interface and how it works are in the first
patch.
This patch (of 4):
Introduce a memcg interface to trigger memory reclaim on a memory cgroup.
Use case: Proactive Reclaim
---------------------------
A userspace proactive reclaimer can continuously probe the memcg to
reclaim a small amount of memory. This gives more accurate and up-to-date
workingset estimation as the LRUs are continuously sorted and can
potentially provide more deterministic memory overcommit behavior. The
memory overcommit controller can provide more proactive response to the
changing behavior of the running applications instead of being reactive.
A userspace reclaimer's purpose in this case is not a complete replacement
for kswapd or direct reclaim, it is to proactively identify memory savings
opportunities and reclaim some amount of cold pages set by the policy to
free up the memory for more demanding jobs or scheduling new jobs.
A user space proactive reclaimer is used in Google data centers.
Additionally, Meta's TMO paper recently referenced a very similar
interface used for user space proactive reclaim:
https://dl.acm.org/doi/pdf/10.1145/3503222.3507731
Benefits of a user space reclaimer:
-----------------------------------
1) More flexible on who should be charged for the cpu of the memory
reclaim. For proactive reclaim, it makes more sense to be centralized.
2) More flexible on dedicating the resources (like cpu). The memory
overcommit controller can balance the cost between the cpu usage and
the memory reclaimed.
3) Provides a way to the applications to keep their LRUs sorted, so,
under memory pressure better reclaim candidates are selected. This
also gives more accurate and uptodate notion of working set for an
application.
Why memory.high is not enough?
------------------------------
- memory.high can be used to trigger reclaim in a memcg and can
potentially be used for proactive reclaim. However there is a big
downside in using memory.high. It can potentially introduce high
reclaim stalls in the target application as the allocations from the
processes or the threads of the application can hit the temporary
memory.high limit.
- Userspace proactive reclaimers usually use feedback loops to decide
how much memory to proactively reclaim from a workload. The metrics
used for this are usually either refaults or PSI, and these metrics will
become messy if the application gets throttled by hitting the high
limit.
- memory.high is a stateful interface, if the userspace proactive
reclaimer crashes for any reason while triggering reclaim it can leave
the application in a bad state.
- If a workload is rapidly expanding, setting memory.high to proactively
reclaim memory can result in actually reclaiming more memory than
intended.
The benefits of such interface and shortcomings of existing interface were
further discussed in this RFC thread:
https://lore.kernel.org/linux-mm/5df21376-7dd1-bf81-8414-32a73cea45dd@google.com/
Interface:
----------
Introducing a very simple memcg interface 'echo 10M > memory.reclaim' to
trigger reclaim in the target memory cgroup.
The interface is introduced as a nested-keyed file to allow for future
optional arguments to be easily added to configure the behavior of
reclaim.
Possible Extensions:
--------------------
- This interface can be extended with an additional parameter or flags
to allow specifying one or more types of memory to reclaim from (e.g.
file, anon, ..).
- The interface can also be extended with a node mask to reclaim from
specific nodes. This has use cases for reclaim-based demotion in memory
tiering systens.
- A similar per-node interface can also be added to support proactive
reclaim and reclaim-based demotion in systems without memcg.
- Add a timeout parameter to make it easier for user space to call the
interface without worrying about being blocked for an undefined amount
of time.
For now, let's keep things simple by adding the basic functionality.
[yosryahmed@google.com: worked on versions v2 onwards, refreshed to
current master, updated commit message based on recent
discussions and use cases]
Link: https://lkml.kernel.org/r/20220425190040.2475377-1-yosryahmed@google.com
Link: https://lkml.kernel.org/r/20220425190040.2475377-2-yosryahmed@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Co-developed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Wei Xu <weixugc@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/admin-guide/cgroup-v2.rst | 21 ++++++++++
mm/memcontrol.c | 45 ++++++++++++++++++++++
2 files changed, 66 insertions(+)
--- a/Documentation/admin-guide/cgroup-v2.rst~memcg-introduce-per-memcg-reclaim-interface
+++ a/Documentation/admin-guide/cgroup-v2.rst
@@ -1208,6 +1208,27 @@ PAGE_SIZE multiple when read back.
high limit is used and monitored properly, this limit's
utility is limited to providing the final safety net.
+ memory.reclaim
+ A write-only nested-keyed file which exists for all cgroups.
+
+ This is a simple interface to trigger memory reclaim in the
+ target cgroup.
+
+ This file accepts a single key, the number of bytes to reclaim.
+ No nested keys are currently supported.
+
+ Example::
+
+ echo "1G" > memory.reclaim
+
+ The interface can be later extended with nested keys to
+ configure the reclaim behavior. For example, specify the
+ type of memory to reclaim from (anon, file, ..).
+
+ Please note that the kernel can over or under reclaim from
+ the target cgroup. If less bytes are reclaimed than the
+ specified amount, -EAGAIN is returned.
+
memory.oom.group
A read-write single value file which exists on non-root
cgroups. The default value is "0".
--- a/mm/memcontrol.c~memcg-introduce-per-memcg-reclaim-interface
+++ a/mm/memcontrol.c
@@ -6360,6 +6360,46 @@ static ssize_t memory_oom_group_write(st
return nbytes;
}
+static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ unsigned int nr_retries = MAX_RECLAIM_RETRIES;
+ unsigned long nr_to_reclaim, nr_reclaimed = 0;
+ int err;
+
+ buf = strstrip(buf);
+ err = page_counter_memparse(buf, "", &nr_to_reclaim);
+ if (err)
+ return err;
+
+ while (nr_reclaimed < nr_to_reclaim) {
+ unsigned long reclaimed;
+
+ if (signal_pending(current))
+ return -EINTR;
+
+ /*
+ * This is the final attempt, drain percpu lru caches in the
+ * hope of introducing more evictable pages for
+ * try_to_free_mem_cgroup_pages().
+ */
+ if (!nr_retries)
+ lru_add_drain_all();
+
+ reclaimed = try_to_free_mem_cgroup_pages(memcg,
+ nr_to_reclaim - nr_reclaimed,
+ GFP_KERNEL, true);
+
+ if (!reclaimed && !nr_retries--)
+ return -EAGAIN;
+
+ nr_reclaimed += reclaimed;
+ }
+
+ return nbytes;
+}
+
static struct cftype memory_files[] = {
{
.name = "current",
@@ -6418,6 +6458,11 @@ static struct cftype memory_files[] = {
.seq_show = memory_oom_group_show,
.write = memory_oom_group_write,
},
+ {
+ .name = "reclaim",
+ .flags = CFTYPE_NS_DELEGATABLE,
+ .write = memory_reclaim,
+ },
{ } /* terminate */
};
_
Patches currently in -mm which might be from shakeelb@google.com are
memcg-introduce-per-memcg-reclaim-interface.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + memcg-introduce-per-memcg-reclaim-interface.patch added to -mm tree
@ 2020-09-12 19:49 akpm
0 siblings, 0 replies; 3+ messages in thread
From: akpm @ 2020-09-12 19:49 UTC (permalink / raw)
To: mm-commits, yang.shi, sjpark, rientjes, mkoutny, mhocko, hannes,
guro, gthelen, shakeelb
The patch titled
Subject: memcg: introduce per-memcg reclaim interface
has been added to the -mm tree. Its filename is
memcg-introduce-per-memcg-reclaim-interface.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/memcg-introduce-per-memcg-reclaim-interface.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@google.com>
Subject: memcg: introduce per-memcg reclaim interface
Introduce an memcg interface to trigger memory reclaim on a memory cgroup.
Use cases:
----------
1) Per-memcg uswapd:
Usually applications consists of combination of latency sensitive
and latency tolerant tasks. For example, tasks serving user requests
vs tasks doing data backup for a database application. At the moment
the kernel does not differentiate between such tasks when the
application hits the memcg limits. So, potentially a latency sensitive
user facing task can get stuck in high reclaim and be throttled by the
kernel.
Similarly there are cases of single process applications having two
set of thread pools where threads from one pool have high scheduling
priority and low latency requirement. One concrete example from our
production is the VMM which have high priority low latency thread pool
for the VCPUs while separate thread pool for stats reporting, I/O
emulation, health checks and other managerial operations. The kernel
memory reclaim does not differentiate between VCPU thread or a
non-latency sensitive thread and a VCPU thread can get stuck in high
reclaim.
One way to resolve this issue is to preemptively trigger the memory
reclaim from a latency tolerant task (uswapd) when the application is
near the limits. Finding 'near the limits' situation is an orthogonal
problem.
2) Proactive reclaim:
This is a similar to the previous use-case, the difference is
instead of waiting for the application to be near its limit to trigger
memory reclaim, continuously pressuring the memcg to reclaim a small
amount of memory. This gives more accurate and uptodate workingset
estimation as the LRUs are continuously sorted and can potentially
provide more deterministic memory overcommit behavior. The memory
overcommit controller can provide more proactive response to the
changing behavior of the running applications instead of being
reactive.
Benefit of user space solution:
-------------------------------
1) More flexible on who should be charged for the cpu of the memory
reclaim. For proactive reclaim, it makes more sense to centralized the
overhead while for uswapd, it makes more sense for the application to
pay for the cpu of the memory reclaim.
2) More flexible on dedicating the resources (like cpu). The memory
overcommit controller can balance the cost between the cpu usage and
the memory reclaimed.
3) Provides a way to the applications to keep their LRUs sorted, so,
under memory pressure better reclaim candidates are selected. This
also gives more accurate and uptodate notion of working set for an
application.
Questions:
----------
1) Why memory.high is not enough?
memory.high can be used to trigger reclaim in a memcg and can
potentially be used for proactive reclaim as well as uswapd use cases.
However there is a big negative in using memory.high. It can
potentially introduce high reclaim stalls in the target application as
the allocations from the processes or the threads of the application
can hit the temporary memory.high limit.
Another issue with memory.high is that it is not delegatable. To
actually use this interface for uswapd, the application has to
introduce another layer of cgroup on whose memory.high it has write
access.
2) Why uswapd safe from self induced reclaim?
This is very similar to the scenario of oomd under global memory
pressure. We can use the similar mechanisms to protect uswapd from
self induced reclaim i.e. memory.min and mlock.
Interface options:
------------------
Introducing a very simple memcg interface 'echo 10M > memory.reclaim' to
trigger reclaim in the target memory cgroup.
In future we might want to reclaim specific type of memory from a memcg,
so, this interface can be extended to allow that. e.g.
$ echo 10M [all|anon|file|kmem] > memory.reclaim
However that should be when we have concrete use-cases for such
functionality. Keep things simple for now.
Link: https://lkml.kernel.org/r/20200909215752.1725525-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/admin-guide/cgroup-v2.rst | 9 +++++
mm/memcontrol.c | 37 ++++++++++++++++++++++
2 files changed, 46 insertions(+)
--- a/Documentation/admin-guide/cgroup-v2.rst~memcg-introduce-per-memcg-reclaim-interface
+++ a/Documentation/admin-guide/cgroup-v2.rst
@@ -1181,6 +1181,15 @@ PAGE_SIZE multiple when read back.
high limit is used and monitored properly, this limit's
utility is limited to providing the final safety net.
+ memory.reclaim
+ A write-only file which exists on non-root cgroups.
+
+ This is a simple interface to trigger memory reclaim in the
+ target cgroup. Write the number of bytes to reclaim to this
+ file and the kernel will try to reclaim that much memory.
+ Please note that the kernel can over or under reclaim from
+ the target cgroup.
+
memory.oom.group
A read-write single value file which exists on non-root
cgroups. The default value is "0".
--- a/mm/memcontrol.c~memcg-introduce-per-memcg-reclaim-interface
+++ a/mm/memcontrol.c
@@ -6423,6 +6423,38 @@ static ssize_t memory_oom_group_write(st
return nbytes;
}
+static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ unsigned int nr_retries = MAX_RECLAIM_RETRIES;
+ unsigned long nr_to_reclaim, nr_reclaimed = 0;
+ int err;
+
+ buf = strstrip(buf);
+ err = page_counter_memparse(buf, "", &nr_to_reclaim);
+ if (err)
+ return err;
+
+ while (nr_reclaimed < nr_to_reclaim) {
+ unsigned long reclaimed;
+
+ if (signal_pending(current))
+ break;
+
+ reclaimed = try_to_free_mem_cgroup_pages(memcg,
+ nr_to_reclaim - nr_reclaimed,
+ GFP_KERNEL, true);
+
+ if (!reclaimed && !nr_retries--)
+ break;
+
+ nr_reclaimed += reclaimed;
+ }
+
+ return nbytes;
+}
+
static struct cftype memory_files[] = {
{
.name = "current",
@@ -6475,6 +6507,11 @@ static struct cftype memory_files[] = {
.seq_show = memory_oom_group_show,
.write = memory_oom_group_write,
},
+ {
+ .name = "reclaim",
+ .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+ .write = memory_reclaim,
+ },
{ } /* terminate */
};
_
Patches currently in -mm which might be from shakeelb@google.com are
memcg-introduce-per-memcg-reclaim-interface.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-04-25 20:18 UTC | newest]
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2022-04-22 21:37 + memcg-introduce-per-memcg-reclaim-interface.patch added to -mm tree Andrew Morton
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2022-04-25 20:18 Andrew Morton
2020-09-12 19:49 akpm
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