Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 18 Dec 2023 12:25:23 +0100 | Subject | Re: [PATCH v4 2/4] mm/ksm: add sysfs knobs for advisor | From | David Hildenbrand <> |
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On 13.12.23 19:27, Stefan Roesch wrote: > This adds four new knobs for the KSM advisor to influence its behaviour. > > The knobs are: > - advisor_mode: > none: no advisor (default) > scan-time: scan time advisor > - advisor_max_cpu: 70 (default, cpu usage percent) > - advisor_min_pages_to_scan: 500 (default) > - advisor_max_pages_to_scan: 30000 (default) > - advisor_target_scan_time: 200 (default in seconds) > > The new values will take effect on the next scan round. > > Signed-off-by: Stefan Roesch <shr@devkernel.io> > --- > mm/ksm.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 139 insertions(+), 3 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 4f7b71a1f3112..f7387a6d02050 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -302,10 +302,10 @@ unsigned long ksm_zero_pages; > static unsigned long ksm_pages_skipped; > > /* Don't scan more than max pages per batch. */ > -static unsigned long ksm_advisor_max_pages = 30000; > +static unsigned long ksm_advisor_max_pages_to_scan = 30000; > > /* At least scan this many pages per batch. */ > -static unsigned long ksm_advisor_min_pages = 500; > +static unsigned long ksm_advisor_min_pages_to_scan = 500; >
That renaming should go into the previous patch.
> /* Min CPU for scanning pages per scan */ > static unsigned int ksm_advisor_min_cpu = 10; > @@ -341,6 +341,16 @@ enum ksm_advisor_type { > }; > static enum ksm_advisor_type ksm_advisor; > > +static void set_advisor_defaults(void) > +{ > + if (ksm_advisor == KSM_ADVISOR_NONE) { > + ksm_thread_pages_to_scan = DEFAULT_PAGES_TO_SCAN; > + } else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) { > + advisor_ctx = (const struct advisor_ctx){ 0 }; > + ksm_thread_pages_to_scan = ksm_advisor_min_pages_to_scan; > + } > +} > + > static inline void advisor_start_scan(void) > { > if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) > @@ -434,7 +444,7 @@ static void scan_time_advisor(void) > > pages = min(pages, per_page_cost * ksm_advisor_max_cpu); > pages = max(pages, per_page_cost * ksm_advisor_min_cpu); > - pages = min(pages, ksm_advisor_max_pages); > + pages = min(pages, ksm_advisor_max_pages_to_scan); > > /* Update advisor context */ > advisor_ctx.change = change; > @@ -3722,6 +3732,127 @@ static ssize_t smart_scan_store(struct kobject *kobj, > } > KSM_ATTR(smart_scan); > > +static ssize_t advisor_mode_show(struct kobject *kobj, > + struct kobj_attribute *attr, char *buf) > +{ > + const char *output; > + > + if (ksm_advisor == KSM_ADVISOR_NONE) > + output = "[none] scan-time"; > + else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) > + output = "none [scan-time]"; > + > + return sysfs_emit(buf, "%s\n", output); > +} > + > +static ssize_t advisor_mode_store(struct kobject *kobj, > + struct kobj_attribute *attr, const char *buf, > + size_t count) > +{ > + if (sysfs_streq("scan-time", buf)) > + ksm_advisor = KSM_ADVISOR_SCAN_TIME; > + else if (sysfs_streq("none", buf)) > + ksm_advisor = KSM_ADVISOR_NONE; > + else > + return -EINVAL; > + > + /* Set advisor default values */ > + set_advisor_defaults();
It probably makes sense to not reset the defaults if the ksm_advisor didn't change.
Apart form that, LGTM.
-- Cheers,
David / dhildenb
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