Re: [PATCH v3] hugetlb: Add hugetlb.*.numa_stat file

From: Muchun Song
Date: Sun Nov 07 2021 - 21:51:48 EST

Next message: Justin Seydou: "Proposal"
Previous message: Wu Bo: "[PATCH] fs: direct-io: use DIV_ROUND_UP helper macro for calculations"
In reply to: Mina Almasry: "Re: [PATCH v3] hugetlb: Add hugetlb.*.numa_stat file"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Mon, Nov 8, 2021 at 7:09 AM Mina Almasry <almasrymina@xxxxxxxxxx> wrote:
>
> On Fri, Nov 5, 2021 at 11:55 PM Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:
> >
> > On Thu, Nov 4, 2021 at 12:53 PM Mina Almasry <almasrymina@xxxxxxxxxx> wrote:
> > >
> > > For hugetlb backed jobs/VMs it's critical to understand the numa
> > > information for the memory backing these jobs to deliver optimal
> > > performance.
> > >
> > > Currently this technically can be queried from /proc/self/numa_maps, but
> > > there are significant issues with that. Namely:
> > > 1. Memory can be mapped on unmapped.
> > > 2. numa_maps are per process and need to be aggregated across all
> > > processes in the cgroup. For shared memory this is more involved as
> > > the userspace needs to make sure it doesn't double count shared
> > > mappings.
> > > 3. I believe querying numa_maps needs to hold the mmap_lock which adds
> > > to the contention on this lock.
> > >
> > > For these reasons I propose simply adding hugetlb.*.numa_stat file,
> > > which shows the numa information of the cgroup similarly to
> > > memory.numa_stat.
> > >
> > > On cgroup-v2:
> > > cat /sys/fs/cgroup/unified/test/hugetlb.2MB.numa_stat
> > > total=2097152 N0=2097152 N1=0
> > >
> > > On cgroup-v1:
> > > cat /sys/fs/cgroup/hugetlb/test/hugetlb.2MB.numa_stat
> > > total=2097152 N0=2097152 N1=0
> > > hierarichal_total=2097152 N0=2097152 N1=0
> > >
> > > This patch was tested manually by allocating hugetlb memory and querying
> > > the hugetlb.*.numa_stat file of the cgroup and its parents.
> > > 
> > > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Shuah Khan <shuah@xxxxxxxxxx>
> > > Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> > > Cc: Oscar Salvador <osalvador@xxxxxxx>
> > > Cc: Michal Hocko <mhocko@xxxxxxxx>
> > > Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> > > Cc: David Rientjes <rientjes@xxxxxxxxxx>
> > > Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
> > > Cc: Jue Wang <juew@xxxxxxxxxx>
> > > Cc: Yang Yao <ygyao@xxxxxxxxxx>
> > > Cc: Joanna Li <joannali@xxxxxxxxxx>
> > > Cc: Cannon Matthews <cannonmatthews@xxxxxxxxxx>
> > > Cc: linux-mm@xxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > >
> > > Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
> > >
> > > ---
> > >
> > > Changes in v3:
> > > - Fixed typos (sorry!)
> > > - Used conventional locations for cgroups mount points in docs/commit
> > > message.
> > > - Updated docs.
> > > - Handle kzalloc_node failure, and proper deallocation of per node data.
> > > - Use struct_size() to calculate the struct size.
> > > - Use nr_node_ids instead of MAX_NUMNODES.
> > > - Updated comments per multi-line comment pattern.
> > >
> > > Changes in v2:
> > > - Fix warning Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > ---
> > > .../admin-guide/cgroup-v1/hugetlb.rst | 4 +
> > > Documentation/admin-guide/cgroup-v2.rst | 5 +
> > > include/linux/hugetlb.h | 4 +-
> > > include/linux/hugetlb_cgroup.h | 7 ++
> > > mm/hugetlb_cgroup.c | 116 ++++++++++++++++--
> > > .../testing/selftests/vm/write_to_hugetlbfs.c | 9 +-
> > > 6 files changed, 132 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/Documentation/admin-guide/cgroup-v1/hugetlb.rst b/Documentation/admin-guide/cgroup-v1/hugetlb.rst
> > > index 338f2c7d7a1c..0fa724d82abb 100644
> > > --- a/Documentation/admin-guide/cgroup-v1/hugetlb.rst
> > > +++ b/Documentation/admin-guide/cgroup-v1/hugetlb.rst
> > > @@ -29,12 +29,14 @@ Brief summary of control files::
> > > hugetlb.<hugepagesize>.max_usage_in_bytes # show max "hugepagesize" hugetlb usage recorded
> > > hugetlb.<hugepagesize>.usage_in_bytes # show current usage for "hugepagesize" hugetlb
> > > hugetlb.<hugepagesize>.failcnt # show the number of allocation failure due to HugeTLB usage limit
> > > + hugetlb.<hugepagesize>.numa_stat # show the numa information of the hugetlb memory charged to this cgroup
> > >
> > > For a system supporting three hugepage sizes (64k, 32M and 1G), the control
> > > files include::
> > >
> > > hugetlb.1GB.limit_in_bytes
> > > hugetlb.1GB.max_usage_in_bytes
> > > + hugetlb.1GB.numa_stat
> > > hugetlb.1GB.usage_in_bytes
> > > hugetlb.1GB.failcnt
> > > hugetlb.1GB.rsvd.limit_in_bytes
> > > @@ -43,6 +45,7 @@ files include::
> > > hugetlb.1GB.rsvd.failcnt
> > > hugetlb.64KB.limit_in_bytes
> > > hugetlb.64KB.max_usage_in_bytes
> > > + hugetlb.64KB.numa_stat
> > > hugetlb.64KB.usage_in_bytes
> > > hugetlb.64KB.failcnt
> > > hugetlb.64KB.rsvd.limit_in_bytes
> > > @@ -51,6 +54,7 @@ files include::
> > > hugetlb.64KB.rsvd.failcnt
> > > hugetlb.32MB.limit_in_bytes
> > > hugetlb.32MB.max_usage_in_bytes
> > > + hugetlb.32MB.numa_stat
> > > hugetlb.32MB.usage_in_bytes
> > > hugetlb.32MB.failcnt
> > > hugetlb.32MB.rsvd.limit_in_bytes
> > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> > > index 4d8c27eca96b..356847f8f008 100644
> > > --- a/Documentation/admin-guide/cgroup-v2.rst
> > > +++ b/Documentation/admin-guide/cgroup-v2.rst
> > > @@ -2252,6 +2252,11 @@ HugeTLB Interface Files
> > > are local to the cgroup i.e. not hierarchical. The file modified event
> > > generated on this file reflects only the local events.
> > >
> > > + hugetlb.<hugepagesize>.numa_stat
> > > + Similar to memory.numa_stat, it shows the numa information of the
> > > + hugetlb pages of <hugepagesize> in this cgroup. Only active in
> > > + use hugetlb pages are included. The per-node values are in bytes.
> > > +
> > > Misc
> > > ----
> > >
> > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> > > index 1faebe1cd0ed..0445faaa636e 100644
> > > --- a/include/linux/hugetlb.h
> > > +++ b/include/linux/hugetlb.h
> > > @@ -613,8 +613,8 @@ struct hstate {
> > > #endif
> > > #ifdef CONFIG_CGROUP_HUGETLB
> > > /* cgroup control files */
> > > - struct cftype cgroup_files_dfl[7];
> > > - struct cftype cgroup_files_legacy[9];
> > > + struct cftype cgroup_files_dfl[8];
> > > + struct cftype cgroup_files_legacy[10];
> > > #endif
> > > char name[HSTATE_NAME_LEN];
> > > };
> > > diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> > > index c137396129db..54ff6ec68ed3 100644
> > > --- a/include/linux/hugetlb_cgroup.h
> > > +++ b/include/linux/hugetlb_cgroup.h
> > > @@ -36,6 +36,11 @@ enum hugetlb_memory_event {
> > > HUGETLB_NR_MEMORY_EVENTS,
> > > };
> > >
> > > +struct hugetlb_cgroup_per_node {
> > > + /* hugetlb usage in bytes over all hstates. */
> > > + unsigned long usage[HUGE_MAX_HSTATE];
> > > +};
> > > +
> > > struct hugetlb_cgroup {
> > > struct cgroup_subsys_state css;
> > >
> > > @@ -57,6 +62,8 @@ struct hugetlb_cgroup {
> > >
> > > /* Handle for "hugetlb.events.local" */
> > > struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
> > > +
> > > + struct hugetlb_cgroup_per_node *nodeinfo[];
> > > };
> > >
> > > static inline struct hugetlb_cgroup *
> > > diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> > > index 5383023d0cca..6be6dfb4f7a7 100644
> > > --- a/mm/hugetlb_cgroup.c
> > > +++ b/mm/hugetlb_cgroup.c
> > > @@ -126,29 +126,59 @@ static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,
> > > }
> > > }
> > >
> > > +static void hugetlb_cgroup_free(struct hugetlb_cgroup *h_cgroup)
> > > +{
> > > + int node;
> > > +
> > > + for_each_node(node) {
> > > + kfree(h_cgroup->nodeinfo[node]);
> > > + }
> >
> > Braces {} are not necessary for single statement blocks.
> >
>
> Will be removed in v4.
>
> > > + kfree(h_cgroup);
> > > +}
> > > +
> > > static struct cgroup_subsys_state *
> > > hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
> > > {
> > > struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
> > > struct hugetlb_cgroup *h_cgroup;
> > > + int node;
> > > +
> > > + h_cgroup = kzalloc(struct_size(h_cgroup, nodeinfo, nr_node_ids),
> > > + GFP_KERNEL);
> > >
> > > - h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
> > > if (!h_cgroup)
> > > return ERR_PTR(-ENOMEM);
> > >
> > > if (!parent_h_cgroup)
> > > root_h_cgroup = h_cgroup;
> > >
> > > + /*
> > > + * TODO: this routine can waste much memory for nodes which will
> > > + * never be onlined. It's better to use memory hotplug callback
> > > + * function.
> > > + */
> > > + for_each_node(node) {
> > > + /* Set node_to_alloc to -1 for offline nodes. */
> > > + int node_to_alloc =
> > > + node_state(node, N_NORMAL_MEMORY) ? node : -1;
> > > + h_cgroup->nodeinfo[node] =
> > > + kzalloc_node(sizeof(struct hugetlb_cgroup_per_node),
> > > + GFP_KERNEL, node_to_alloc);
> > > + if (!h_cgroup->nodeinfo[node])
> > > + goto fail_alloc_nodeinfo;
> > > + }
> > > +
> > > hugetlb_cgroup_init(h_cgroup, parent_h_cgroup);
> > > return &h_cgroup->css;
> > > +
> > > +fail_alloc_nodeinfo:
> > > + hugetlb_cgroup_free(h_cgroup);
> > > + return ERR_PTR(-ENOMEM);
> > > }
> > >
> > > static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
> > > {
> > > - struct hugetlb_cgroup *h_cgroup;
> > > -
> > > - h_cgroup = hugetlb_cgroup_from_css(css);
> > > - kfree(h_cgroup);
> > > + hugetlb_cgroup_free(hugetlb_cgroup_from_css(css));
> > > }
> > >
> > > /*
> > > @@ -292,7 +322,9 @@ static void __hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
> > > return;
> > >
> > > __set_hugetlb_cgroup(page, h_cg, rsvd);
> > > - return;
> > > + if (!rsvd && h_cg)
> > > + h_cg->nodeinfo[page_to_nid(page)]->usage[idx] += nr_pages
> > > + << PAGE_SHIFT;
> >
> > How about changing the unit from byte to page? In this case, we
> > do not need to do shift operations here. When the user reads
> > numa_stat, then converting the pages to bytes for them.
> >
>
> So all the other hugetlb_cgroup interfaces (max, current,
> usage_in_bytes, limit_in_bytes), are in bytes and not pages, and
> memory.numa_stat is also in bytes. I think providing consistency here
> is a really good thing.

I mean accounting with pages but showing with bytes, which is more
efficient and does not break consistency.

>
> > > }
> > >
> > > void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
> > > @@ -331,7 +363,9 @@ static void __hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
> > >
> > > if (rsvd)
> > > css_put(&h_cg->css);
> > > -
> > > + else
> > > + h_cg->nodeinfo[page_to_nid(page)]->usage[idx] -= nr_pages
> > > + << PAGE_SHIFT;
> > > return;
> > > }
> > >
> > > @@ -421,6 +455,58 @@ enum {
> > > RES_RSVD_FAILCNT,
> > > };
> > >
> > > +static int hugetlb_cgroup_read_numa_stat(struct seq_file *seq, void *dummy)
> > > +{
> > > + int nid;
> > > + struct cftype *cft = seq_cft(seq);
> > > + int idx = MEMFILE_IDX(cft->private);
> > > + bool legacy = MEMFILE_ATTR(cft->private);
> > > + struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
> > > + struct cgroup_subsys_state *css;
> > > + unsigned long usage;
> > > +
> > > + if (legacy) {
> > > + /* Add up usage across all nodes for the non-hierarchical total. */
> > > + usage = 0;
> > > + for_each_node_state(nid, N_MEMORY)
> > > + usage += h_cg->nodeinfo[nid]->usage[idx];
> > > + seq_printf(seq, "total=%lu", usage);

Here it could be like this.

seq_printf(seq, "total=%lu", usage * PAGE_SIZE);

Thanks.

> > > +
> > > + /* Simply print the per-node usage for the non-hierarchical total. */
> > > + for_each_node_state(nid, N_MEMORY)
> > > + seq_printf(seq, " N%d=%lu", nid,
> > > + h_cg->nodeinfo[nid]->usage[idx]);
> > > + seq_putc(seq, '\n');
> > > + }
> > > +
> > > + /*
> > > + * The hierarchical total is pretty much the value recorded by the
> > > + * counter, so use that.
> > > + */
> > > + seq_printf(seq, "%stotal=%lu", legacy ? "hierarichal_" : "",
> > > + page_counter_read(&h_cg->hugepage[idx]) * PAGE_SIZE);
> > > +
> > > + /*
> > > + * For each node, transverse the css tree to obtain the hierarichal
> > > + * node usage.
> > > + */
> > > + for_each_node_state(nid, N_MEMORY) {
> > > + usage = 0;
> > > + rcu_read_lock();
> > > + css_for_each_descendant_pre(css, &h_cg->css) {
> > > + usage += hugetlb_cgroup_from_css(css)
> > > + ->nodeinfo[nid]
> > > + ->usage[idx];
> > > + }
> > > + rcu_read_unlock();
> > > + seq_printf(seq, " N%d=%lu", nid, usage);
> > > + }
> > > +
> > > + seq_putc(seq, '\n');
> > > +
> > > + return 0;
> > > +}
> > > +
> > > static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
> > > struct cftype *cft)
> > > {
> > > @@ -671,8 +757,14 @@ static void __init __hugetlb_cgroup_file_dfl_init(int idx)
> > > events_local_file[idx]);
> > > cft->flags = CFTYPE_NOT_ON_ROOT;
> > >
> > > - /* NULL terminate the last cft */
> > > + /* Add the numa stat file */
> > > cft = &h->cgroup_files_dfl[6];
> > > + snprintf(cft->name, MAX_CFTYPE_NAME, "%s.numa_stat", buf);
> > > + cft->seq_show = hugetlb_cgroup_read_numa_stat;
> > > + cft->flags = CFTYPE_NOT_ON_ROOT;
> > > +
> > > + /* NULL terminate the last cft */
> > > + cft = &h->cgroup_files_dfl[7];
> > > memset(cft, 0, sizeof(*cft));
> > >
> > > WARN_ON(cgroup_add_dfl_cftypes(&hugetlb_cgrp_subsys,
> > > @@ -742,8 +834,14 @@ static void __init __hugetlb_cgroup_file_legacy_init(int idx)
> > > cft->write = hugetlb_cgroup_reset;
> > > cft->read_u64 = hugetlb_cgroup_read_u64;
> > >
> > > + /* Add the numa stat file */
> > > + cft = &h->cgroup_files_dfl[8];
> > > + snprintf(cft->name, MAX_CFTYPE_NAME, "%s.numa_stat", buf);
> > > + cft->private = MEMFILE_PRIVATE(idx, 1);
> > > + cft->seq_show = hugetlb_cgroup_read_numa_stat;
> > > +
> > > /* NULL terminate the last cft */
> > > - cft = &h->cgroup_files_legacy[8];
> > > + cft = &h->cgroup_files_legacy[9];
> > > memset(cft, 0, sizeof(*cft));
> > >
> > > WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
> > > diff --git a/tools/testing/selftests/vm/write_to_hugetlbfs.c b/tools/testing/selftests/vm/write_to_hugetlbfs.c
> > > index 6a2caba19ee1..d2da6315a40c 100644
> > > --- a/tools/testing/selftests/vm/write_to_hugetlbfs.c
> > > +++ b/tools/testing/selftests/vm/write_to_hugetlbfs.c
> > > @@ -37,8 +37,8 @@ static int shmid;
> > > static void exit_usage(void)
> > > {
> > > printf("Usage: %s -p <path to hugetlbfs file> -s <size to map> "
> > > - "[-m <0=hugetlbfs | 1=mmap(MAP_HUGETLB)>] [-l] [-r] "
> > > - "[-o] [-w] [-n]\n",
> > > + "[-m <0=hugetlbfs | 1=mmap(MAP_HUGETLB)>] [-l(sleep)] [-r(private)] "
> > > + "[-o(populate)] [-w(rite)] [-n(o-reserve)]\n",
> >
> > Why do those changes? It seems like it does not belong
> > to this patch. Please explain why you did this in changelog
> > and separate those lines into another patch.
> >
> > Thanks.
> >
>
> So I used writo_to_hugetlbfs to test this patch, and I forgot what the
> flags do so I clarified them, but sure yes these changes aren't
> related to numa_stat. I'll drop them from v4 and I can always upload
> them later.
>
> > > self);
> > > exit(EXIT_FAILURE);
> > > }
> > > @@ -161,6 +161,11 @@ int main(int argc, char **argv)
> > > else
> > > printf("RESERVE mapping.\n");
> > >
> > > + if (want_sleep)
> > > + printf("Sleeping\n");
> > > + else
> > > + printf("Not sleeping\n");
> > > +
> > > switch (method) {
> > > case HUGETLBFS:
> > > printf("Allocating using HUGETLBFS.\n");
> > > --
> > > 2.33.1.1089.g2158813163f-goog

Next message: Justin Seydou: "Proposal"
Previous message: Wu Bo: "[PATCH] fs: direct-io: use DIV_ROUND_UP helper macro for calculations"
In reply to: Mina Almasry: "Re: [PATCH v3] hugetlb: Add hugetlb.*.numa_stat file"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]