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mm/damon/schemes: implement time quota

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The size quota feature of DAMOS is useful for IO resource-critical
systems, but not so intuitive for CPU time-critical systems.  Systems
using zram or zswap-like swap device would be examples.

To provide another intuitive ways for such systems, this implements
time-based quota for DAMON-based Operation Schemes.  If the quota is
set, DAMOS tries to use only up to the user-defined quota of CPU time
within a given time window.

Link: https://lkml.kernel.org/r/20211019150731.16699-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
SeongJae Park 2021-11-05 13:47:23 -07:00 committed by Linus Torvalds
parent 50585192bc
commit 1cd2430300
2 changed files with 60 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
include/linux/damon.h
View File

@ -91,20 +91,35 @@ enum damos_action {
/**
* struct damos_quota - Controls the aggressiveness of the given scheme.
* @ms: Maximum milliseconds that the scheme can use.
* @sz: Maximum bytes of memory that the action can be applied.
* @reset_interval: Charge reset interval in milliseconds.
*
* To avoid consuming too much CPU time or IO resources for applying the
* &struct damos->action to large memory, DAMON allows users to set a size
* quota. The quota can be set by writing non-zero values to &sz. If the size
* quota is set, DAMON tries to apply the action only up to &sz bytes within
* &reset_interval.
* &struct damos->action to large memory, DAMON allows users to set time and/or
* size quotas. The quotas can be set by writing non-zero values to &ms and
* &sz, respectively. If the time quota is set, DAMON tries to use only up to
* &ms milliseconds within &reset_interval for applying the action. If the
* size quota is set, DAMON tries to apply the action only up to &sz bytes
* within &reset_interval.
*
* Internally, the time quota is transformed to a size quota using estimated
* throughput of the scheme's action. DAMON then compares it against &sz and
* uses smaller one as the effective quota.
*/
struct damos_quota {
unsigned long ms;
unsigned long sz;
unsigned long reset_interval;
/* private: For charging the quota */
/* private: */
/* For throughput estimation */
unsigned long total_charged_sz;
unsigned long total_charged_ns;
unsigned long esz; /* Effective size quota in bytes */
/* For charging the quota */
unsigned long charged_sz;
unsigned long charged_from;
struct damon_target *charge_target_from;

45
mm/damon/core.c
View File

@ -107,8 +107,12 @@ struct damos *damon_new_scheme(
scheme->stat_sz = 0;
INIT_LIST_HEAD(&scheme->list);
scheme->quota.ms = quota->ms;
scheme->quota.sz = quota->sz;
scheme->quota.reset_interval = quota->reset_interval;
scheme->quota.total_charged_sz = 0;
scheme->quota.total_charged_ns = 0;
scheme->quota.esz = 0;
scheme->quota.charged_sz = 0;
scheme->quota.charged_from = 0;
scheme->quota.charge_target_from = NULL;
@ -550,9 +554,10 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
damon_for_each_scheme(s, c) {
struct damos_quota *quota = &s->quota;
unsigned long sz = r->ar.end - r->ar.start;
struct timespec64 begin, end;
/* Check the quota */
if (quota->sz && quota->charged_sz >= quota->sz)
if (quota->esz && quota->charged_sz >= quota->esz)
continue;
/* Skip previously charged regions */
@ -597,16 +602,21 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
/* Apply the scheme */
if (c->primitive.apply_scheme) {
if (quota->sz && quota->charged_sz + sz > quota->sz) {
sz = ALIGN_DOWN(quota->sz - quota->charged_sz,
if (quota->esz &&
quota->charged_sz + sz > quota->esz) {
sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
DAMON_MIN_REGION);
if (!sz)
goto update_stat;
damon_split_region_at(c, t, r, sz);
}
ktime_get_coarse_ts64(&begin);
c->primitive.apply_scheme(c, t, r, s);
ktime_get_coarse_ts64(&end);
quota->total_charged_ns += timespec64_to_ns(&end) -
timespec64_to_ns(&begin);
quota->charged_sz += sz;
if (quota->sz && quota->charged_sz >= quota->sz) {
if (quota->esz && quota->charged_sz >= quota->esz) {
quota->charge_target_from = t;
quota->charge_addr_from = r->ar.end + 1;
}
@ -620,6 +630,29 @@ update_stat:
}
}
/* Shouldn't be called if quota->ms and quota->sz are zero */
static void damos_set_effective_quota(struct damos_quota *quota)
{
unsigned long throughput;
unsigned long esz;
if (!quota->ms) {
quota->esz = quota->sz;
return;
}
if (quota->total_charged_ns)
throughput = quota->total_charged_sz * 1000000 /
quota->total_charged_ns;
else
throughput = PAGE_SIZE * 1024;
esz = throughput * quota->ms;
if (quota->sz && quota->sz < esz)
esz = quota->sz;
quota->esz = esz;
}
static void kdamond_apply_schemes(struct damon_ctx *c)
{
struct damon_target *t;
@ -629,15 +662,17 @@ static void kdamond_apply_schemes(struct damon_ctx *c)
damon_for_each_scheme(s, c) {
struct damos_quota *quota = &s->quota;
if (!quota->sz)
if (!quota->ms && !quota->sz)
continue;
/* New charge window starts */
if (time_after_eq(jiffies, quota->charged_from +
msecs_to_jiffies(
quota->reset_interval))) {
quota->total_charged_sz += quota->charged_sz;
quota->charged_from = jiffies;
quota->charged_sz = 0;
damos_set_effective_quota(quota);
}
}