From nobody Fri Dec 19 11:13:31 2025 Received: from 66-220-144-179.mail-mxout.facebook.com (66-220-144-179.mail-mxout.facebook.com [66.220.144.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A3AC76093 for ; Mon, 18 Dec 2023 23:11:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=devkernel.io Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=devkernel.io Received: by devbig1114.prn1.facebook.com (Postfix, from userid 425415) id 1568F111427AE; Mon, 18 Dec 2023 15:10:56 -0800 (PST) From: Stefan Roesch To: kernel-team@fb.com Cc: shr@devkernel.io, akpm@linux-foundation.org, david@redhat.com, hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v5 2/4] mm/ksm: add sysfs knobs for advisor Date: Mon, 18 Dec 2023 15:10:52 -0800 Message-Id: <20231218231054.1625219-3-shr@devkernel.io> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20231218231054.1625219-1-shr@devkernel.io> References: <20231218231054.1625219-1-shr@devkernel.io> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Acked-by: David Hildenbrand --- mm/ksm.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) diff --git a/mm/ksm.c b/mm/ksm.c index 59911700695f7..10e2696907250 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -338,6 +338,25 @@ enum ksm_advisor_type { }; static enum ksm_advisor_type ksm_advisor; =20 +#ifdef CONFIG_SYSFS +/* + * Only called through the sysfs control interface: + */ + +/* At least scan this many pages per batch. */ +static unsigned long ksm_advisor_min_pages_to_scan =3D 500; + +static void set_advisor_defaults(void) +{ + if (ksm_advisor =3D=3D KSM_ADVISOR_NONE) { + ksm_thread_pages_to_scan =3D DEFAULT_PAGES_TO_SCAN; + } else if (ksm_advisor =3D=3D KSM_ADVISOR_SCAN_TIME) { + advisor_ctx =3D (const struct advisor_ctx){ 0 }; + ksm_thread_pages_to_scan =3D ksm_advisor_min_pages_to_scan; + } +} +#endif /* CONFIG_SYSFS */ + static inline void advisor_start_scan(void) { if (ksm_advisor =3D=3D KSM_ADVISOR_SCAN_TIME) @@ -3723,6 +3742,130 @@ static ssize_t smart_scan_store(struct kobject *kob= j, } KSM_ATTR(smart_scan); =20 +static ssize_t advisor_mode_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + const char *output; + + if (ksm_advisor =3D=3D KSM_ADVISOR_NONE) + output =3D "[none] scan-time"; + else if (ksm_advisor =3D=3D KSM_ADVISOR_SCAN_TIME) + output =3D "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) +{ + enum ksm_advisor_type curr_advisor =3D ksm_advisor; + + if (sysfs_streq("scan-time", buf)) + ksm_advisor =3D KSM_ADVISOR_SCAN_TIME; + else if (sysfs_streq("none", buf)) + ksm_advisor =3D KSM_ADVISOR_NONE; + else + return -EINVAL; + + /* Set advisor default values */ + if (curr_advisor !=3D ksm_advisor) + set_advisor_defaults(); + + return count; +} +KSM_ATTR(advisor_mode); + +static ssize_t advisor_max_cpu_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%u\n", ksm_advisor_max_cpu); +} + +static ssize_t advisor_max_cpu_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err; + unsigned long value; + + err =3D kstrtoul(buf, 10, &value); + if (err) + return -EINVAL; + + ksm_advisor_max_cpu =3D value; + return count; +} +KSM_ATTR(advisor_max_cpu); + +static ssize_t advisor_min_pages_to_scan_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lu\n", ksm_advisor_min_pages_to_scan); +} + +static ssize_t advisor_min_pages_to_scan_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err; + unsigned long value; + + err =3D kstrtoul(buf, 10, &value); + if (err) + return -EINVAL; + + ksm_advisor_min_pages_to_scan =3D value; + return count; +} +KSM_ATTR(advisor_min_pages_to_scan); + +static ssize_t advisor_max_pages_to_scan_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lu\n", ksm_advisor_max_pages_to_scan); +} + +static ssize_t advisor_max_pages_to_scan_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err; + unsigned long value; + + err =3D kstrtoul(buf, 10, &value); + if (err) + return -EINVAL; + + ksm_advisor_max_pages_to_scan =3D value; + return count; +} +KSM_ATTR(advisor_max_pages_to_scan); + +static ssize_t advisor_target_scan_time_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lu\n", ksm_advisor_target_scan_time); +} + +static ssize_t advisor_target_scan_time_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err; + unsigned long value; + + err =3D kstrtoul(buf, 10, &value); + if (err) + return -EINVAL; + if (value < 1) + return -EINVAL; + + ksm_advisor_target_scan_time =3D value; + return count; +} +KSM_ATTR(advisor_target_scan_time); + static struct attribute *ksm_attrs[] =3D { &sleep_millisecs_attr.attr, &pages_to_scan_attr.attr, @@ -3745,6 +3888,11 @@ static struct attribute *ksm_attrs[] =3D { &use_zero_pages_attr.attr, &general_profit_attr.attr, &smart_scan_attr.attr, + &advisor_mode_attr.attr, + &advisor_max_cpu_attr.attr, + &advisor_min_pages_to_scan_attr.attr, + &advisor_max_pages_to_scan_attr.attr, + &advisor_target_scan_time_attr.attr, NULL, }; =20 --=20 2.39.3