| Message ID | 20240702125728.2743143-1-xiujianfeng@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [-next] mm/hugetlb_cgroup: introduce peak and rsvd.peak to v2 | expand |
On Tue, 2 Jul 2024 12:57:28 +0000 Xiu Jianfeng <xiujianfeng@huawei.com> wrote: > Introduce peak and rsvd.peak to v2 to show the historical maximum > usage of resources, as in some scenarios it is necessary to configure > the value of max/rsvd.max based on the peak usage of resources. "in some scenarios it is necessary" is not a strong statement. It would be helpful to fully describe these scenarios so that others can better understand the value of this change.
On 2024/7/3 9:58, Andrew Morton wrote: > On Tue, 2 Jul 2024 12:57:28 +0000 Xiu Jianfeng <xiujianfeng@huawei.com> wrote: > >> Introduce peak and rsvd.peak to v2 to show the historical maximum >> usage of resources, as in some scenarios it is necessary to configure >> the value of max/rsvd.max based on the peak usage of resources. > > "in some scenarios it is necessary" is not a strong statement. It > would be helpful to fully describe these scenarios so that others can > better understand the value of this change. > Hi Andrew, Is the following description acceptable for you? Since HugeTLB doesn't support page reclaim, enforcing the limit at page fault time implies that, the application will get SIGBUS signal if it tries to fault in HugeTLB pages beyond its limit. Therefore the application needs to know exactly how many HugeTLB pages it uses before hand, and the sysadmin needs to make sure that there are enough available on the machine for all the users to avoid processes getting SIGBUS. When running some open-source software, it may not be possible to know the exact amount of hugetlb it consumes, so cannot correctly configure the max value. If there is a peak metric, we can run the open-source software first and then configure the max based on the peak value. In cgroup v1, the hugetlb controller provides the max_usage_in_bytes and rsvd.max_usage_in_bytes interface to display the historical maximum usage, so introduce peak and rsvd.peak to v2 to address this issue.
On Wed, 3 Jul 2024 10:45:56 +0800 xiujianfeng <xiujianfeng@huawei.com> wrote: > > > On 2024/7/3 9:58, Andrew Morton wrote: > > On Tue, 2 Jul 2024 12:57:28 +0000 Xiu Jianfeng <xiujianfeng@huawei.com> wrote: > > > >> Introduce peak and rsvd.peak to v2 to show the historical maximum > >> usage of resources, as in some scenarios it is necessary to configure > >> the value of max/rsvd.max based on the peak usage of resources. > > > > "in some scenarios it is necessary" is not a strong statement. It > > would be helpful to fully describe these scenarios so that others can > > better understand the value of this change. > > > > Hi Andrew, > > Is the following description acceptable for you? > > > Since HugeTLB doesn't support page reclaim, enforcing the limit at > page fault time implies that, the application will get SIGBUS signal > if it tries to fault in HugeTLB pages beyond its limit. Therefore the > application needs to know exactly how many HugeTLB pages it uses before > hand, and the sysadmin needs to make sure that there are enough > available on the machine for all the users to avoid processes getting > SIGBUS. > > When running some open-source software, it may not be possible to know > the exact amount of hugetlb it consumes, so cannot correctly configure > the max value. If there is a peak metric, we can run the open-source > software first and then configure the max based on the peak value. > In cgroup v1, the hugetlb controller provides the max_usage_in_bytes > and rsvd.max_usage_in_bytes interface to display the historical maximum > usage, so introduce peak and rsvd.peak to v2 to address this issue. Super, thanks for doing this. It's getting late in the cycle, but the patch is simple so I'll add it to mm-unstable for additional exposure. Hopefully some others can offer their thoughts on the desirability of this.
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index ae0fdb6fc618..97d19968230a 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -2607,6 +2607,14 @@ HugeTLB Interface Files hugetlb pages of <hugepagesize> in this cgroup. Only active in use hugetlb pages are included. The per-node values are in bytes. + hugetlb.<hugepagesize>.peak + Show historical maximum usage for "hugepagesize" hugetlb. It exists + for all the cgroup except root. + + hugetlb.<hugepagesize>.rsvd.peak + Show historical maximum usage for "hugepagesize" hugetlb reservations. + It exists for all the cgroup except root. + Misc ---- diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c index 4ff238ba1250..f443a56409a9 100644 --- a/mm/hugetlb_cgroup.c +++ b/mm/hugetlb_cgroup.c @@ -583,6 +583,13 @@ static int hugetlb_cgroup_read_u64_max(struct seq_file *seq, void *v) else seq_printf(seq, "%llu\n", val * PAGE_SIZE); break; + case RES_RSVD_MAX_USAGE: + counter = &h_cg->rsvd_hugepage[idx]; + fallthrough; + case RES_MAX_USAGE: + val = (u64)counter->watermark; + seq_printf(seq, "%llu\n", val * PAGE_SIZE); + break; default: BUG(); } @@ -739,6 +746,18 @@ static struct cftype hugetlb_dfl_tmpl[] = { .seq_show = hugetlb_cgroup_read_u64_max, .flags = CFTYPE_NOT_ON_ROOT, }, + { + .name = "peak", + .private = RES_MAX_USAGE, + .seq_show = hugetlb_cgroup_read_u64_max, + .flags = CFTYPE_NOT_ON_ROOT, + }, + { + .name = "rsvd.peak", + .private = RES_RSVD_MAX_USAGE, + .seq_show = hugetlb_cgroup_read_u64_max, + .flags = CFTYPE_NOT_ON_ROOT, + }, { .name = "events", .seq_show = hugetlb_events_show,
Introduce peak and rsvd.peak to v2 to show the historical maximum usage of resources, as in some scenarios it is necessary to configure the value of max/rsvd.max based on the peak usage of resources. Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> --- Documentation/admin-guide/cgroup-v2.rst | 8 ++++++++ mm/hugetlb_cgroup.c | 19 +++++++++++++++++++ 2 files changed, 27 insertions(+)