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imf02.hostedemail.com; dkim=none; dmarc=none; spf=neutral (imf02.hostedemail.com: 66.220.144.178 is neither permitted nor denied by domain of shr@devkernel.io) smtp.mailfrom=shr@devkernel.io ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1681269786; a=rsa-sha256; cv=none; b=tTHAp/Wx8+B2gRpGj2uDLrsB/+DadCTHXF6kjGW5ZFQ6IgjAxn+jcetPVnOguKd682dMqO tXC5z+aSpxyNu5my2PX+LxS8Cg+KwXnrIfooERb++DtXQOZnOi/LPYHLZHFDqsQOqG7aC4 o16s2V+T74oBgnSAi2x3vITTUvW+2HI= Received: by devbig1114.prn1.facebook.com (Postfix, from userid 425415) id A797A32C5B0B; Tue, 11 Apr 2023 20:17:03 -0700 (PDT) From: Stefan Roesch To: kernel-team@fb.com Cc: shr@devkernel.io, linux-mm@kvack.org, riel@surriel.com, mhocko@suse.com, david@redhat.com, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, hannes@cmpxchg.org, willy@infradead.org, Bagas Sanjaya Subject: [PATCH v6 2/3] mm: add new KSM process and sysfs knobs Date: Tue, 11 Apr 2023 20:16:47 -0700 Message-Id: <20230412031648.2206875-3-shr@devkernel.io> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230412031648.2206875-1-shr@devkernel.io> References: <20230412031648.2206875-1-shr@devkernel.io> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 774C180007 X-Stat-Signature: qesen7mxd6fjw59uuc61pcy3jaq9tfww X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1681269786-137712 X-HE-Meta: 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 79N+VHCw Sd/Kmrmq3RhBxETOuU+xUfj+2ERlLu2EbufxdIJP7mM4POpCW8SY8519GR83bepbdEvyiKLBOKdLWcv5c8hk3ulPKVc5FMNBB933cqhgAPkBfXJfvCugtRTL5oDz+xiRx5Ja4xNDg93NPKM+FBo63lEX+b11O315IE9rOlLYEptc/XbNaGsJwCYn8sYPeCOVDkldZ/aASC7fqp9CnpUHzQPTsWNs7WURf4zXSDnDJ36wIPIWEBlF45x+7/sbayWYLFhiM2ENIvEjpypHb+t7BcOqH6V4BIS7JpnJDBFYQMszkYCX2cuVJwh3DDNq5enSH72jgcaBqKdJA6jCUw/w7RVg9wpytLdlqlmnUxTy8StUE2nR4rkhs8vFvcEKofuEl7nWdTFd2ml7vn3loiipFj2MYu5YcSN+OfSVpmOhtEhnX1To= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This adds the general_profit KSM sysfs knob and the process profit metric knobs to ksm_stat. 1) expose general_profit metric The documentation mentions a general profit metric, however this metric is not calculated. In addition the formula depends on the size of internal structures, which makes it more difficult for an administrator to make the calculation. Adding the metric for a better user experience. 2) document general_profit sysfs knob 3) calculate ksm process profit metric The ksm documentation mentions the process profit metric and how to calculate it. This adds the calculation of the metric. 4) mm: expose ksm process profit metric in ksm_stat This exposes the ksm process profit metric in /proc//ksm_stat. The documentation mentions the formula for the ksm process profit metric, however it does not calculate it. In addition the formula depends on the size of internal structures. So it makes sense to expose it. 5) document new procfs ksm knobs Signed-off-by: Stefan Roesch Reviewed-by: Bagas Sanjaya Acked-by: David Hildenbrand Cc: David Hildenbrand Cc: Johannes Weiner Cc: Michal Hocko Cc: Rik van Riel Signed-off-by: Andrew Morton --- Documentation/ABI/testing/sysfs-kernel-mm-ksm | 8 +++++++ Documentation/admin-guide/mm/ksm.rst | 5 ++++- fs/proc/base.c | 3 +++ include/linux/ksm.h | 4 ++++ mm/ksm.c | 21 +++++++++++++++++++ 5 files changed, 40 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-ksm b/Documentatio= n/ABI/testing/sysfs-kernel-mm-ksm index d244674a9480..6041a025b65a 100644 --- a/Documentation/ABI/testing/sysfs-kernel-mm-ksm +++ b/Documentation/ABI/testing/sysfs-kernel-mm-ksm @@ -51,3 +51,11 @@ Description: Control merging pages across different NU= MA nodes. =20 When it is set to 0 only pages from the same node are merged, otherwise pages from all nodes can be merged together (default). + +What: /sys/kernel/mm/ksm/general_profit +Date: April 2023 +KernelVersion: 6.4 +Contact: Linux memory management mailing list +Description: Measure how effective KSM is. + general_profit: how effective is KSM. The formula for the + calculation is in Documentation/admin-guide/mm/ksm.rst. diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-g= uide/mm/ksm.rst index 270560fef3b2..bc1dd830dd49 100644 --- a/Documentation/admin-guide/mm/ksm.rst +++ b/Documentation/admin-guide/mm/ksm.rst @@ -157,6 +157,8 @@ stable_node_chains_prune_millisecs =20 The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm= /ksm/``: =20 +general_profit + how effective is KSM. The calculation is explained below. pages_shared how many shared pages are being used pages_sharing @@ -214,7 +216,8 @@ several times, which are unprofitable memory consumed= . ksm_rmap_items * sizeof(rmap_item). =20 where ksm_merging_pages is shown under the directory ``/proc//``= , - and ksm_rmap_items is shown in ``/proc//ksm_stat``. + and ksm_rmap_items is shown in ``/proc//ksm_stat``. The process = profit + is also shown in ``/proc//ksm_stat`` as ksm_process_profit. =20 From the perspective of application, a high ratio of ``ksm_rmap_items`` = to ``ksm_merging_pages`` means a bad madvise-applied policy, so developers = or diff --git a/fs/proc/base.c b/fs/proc/base.c index 07463ad4a70a..cb42bb021995 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -96,6 +96,7 @@ #include #include #include +#include #include #include "internal.h" #include "fd.h" @@ -3208,6 +3209,8 @@ static int proc_pid_ksm_stat(struct seq_file *m, st= ruct pid_namespace *ns, if (mm) { seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items); seq_printf(m, "zero_pages_sharing %lu\n", mm->ksm_zero_pages_sharing); + seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages); + seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm)); mmput(mm); } =20 diff --git a/include/linux/ksm.h b/include/linux/ksm.h index f24f9faf1561..63cb491b1740 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -60,6 +60,10 @@ struct page *ksm_might_need_to_copy(struct page *page, void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc); void folio_migrate_ksm(struct folio *newfolio, struct folio *folio); =20 +#ifdef CONFIG_PROC_FS +long ksm_process_profit(struct mm_struct *); +#endif /* CONFIG_PROC_FS */ + #else /* !CONFIG_KSM */ =20 static inline void ksm_add_vma(struct vm_area_struct *vma) diff --git a/mm/ksm.c b/mm/ksm.c index ab95ae0f9def..7982bac15d8c 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -3042,6 +3042,14 @@ static void wait_while_offlining(void) } #endif /* CONFIG_MEMORY_HOTREMOVE */ =20 +#ifdef CONFIG_PROC_FS +long ksm_process_profit(struct mm_struct *mm) +{ + return mm->ksm_merging_pages * PAGE_SIZE - + mm->ksm_rmap_items * sizeof(struct ksm_rmap_item); +} +#endif /* CONFIG_PROC_FS */ + #ifdef CONFIG_SYSFS /* * This all compiles without CONFIG_SYSFS, but is a waste of space. @@ -3313,6 +3321,18 @@ static ssize_t zero_pages_sharing_show(struct kobj= ect *kobj, } KSM_ATTR_RO(zero_pages_sharing); =20 +static ssize_t general_profit_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + long general_profit; + + general_profit =3D ksm_pages_sharing * PAGE_SIZE - + ksm_rmap_items * sizeof(struct ksm_rmap_item); + + return sysfs_emit(buf, "%ld\n", general_profit); +} +KSM_ATTR_RO(general_profit); + static ssize_t stable_node_dups_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { @@ -3378,6 +3398,7 @@ static struct attribute *ksm_attrs[] =3D { &stable_node_dups_attr.attr, &stable_node_chains_prune_millisecs_attr.attr, &use_zero_pages_attr.attr, + &general_profit_attr.attr, NULL, }; =20 --=20 2.31.1