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Message-ID: <747d1319-f746-4379-bf88-a0f6c3f558b4@linux.alibaba.com>
Date: Fri, 9 Aug 2024 16:31:21 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Ryan Roberts <ryan.roberts@....com>,
Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins <hughd@...gle.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
David Hildenbrand <david@...hat.com>, Barry Song <baohua@...nel.org>,
Lance Yang <ioworker0@...il.com>, Gavin Shan <gshan@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 2/2] mm: Tidy up shmem mTHP controls and stats
On 2024/8/8 19:18, Ryan Roberts wrote:
> Previously we had a situation where shmem mTHP controls and stats were
> not exposed for some supported sizes and were exposed for some
> unsupported sizes. So let's clean that up.
>
> Anon mTHP can support all large orders [2, PMD_ORDER]. But shmem can
> support all large orders [1, MAX_PAGECACHE_ORDER]. However, per-size
> shmem controls and stats were previously being exposed for all the anon
> mTHP orders, meaning order-1 was not present, and for arm64 64K base
> pages, orders 12 and 13 were exposed but were not supported internally.
>
> Tidy this all up by defining ctrl and stats attribute groups for anon
> and file separately. Anon ctrl and stats groups are populated for all
> orders in THP_ORDERS_ALL_ANON and file ctrl and stats groups are
> populated for all orders in THP_ORDERS_ALL_FILE_DEFAULT.
>
> Additionally, create "any" ctrl and stats attribute groups which are
> populated for all orders in (THP_ORDERS_ALL_ANON |
> THP_ORDERS_ALL_FILE_DEFAULT). swpout stats use this since they apply to
> anon and shmem.
>
> The side-effect of all this is that different hugepage-*kB directories
> contain different sets of controls and stats, depending on which memory
> types support that size. This approach is preferred over the
> alternative, which is to populate dummy controls and stats for memory
> types that do not support a given size.
>
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---
> mm/huge_memory.c | 144 +++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 114 insertions(+), 30 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 0c3075ee00012..082d86b7c6c2f 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -482,8 +482,8 @@ static void thpsize_release(struct kobject *kobj);
> static DEFINE_SPINLOCK(huge_anon_orders_lock);
> static LIST_HEAD(thpsize_list);
>
> -static ssize_t thpsize_enabled_show(struct kobject *kobj,
> - struct kobj_attribute *attr, char *buf)
> +static ssize_t anon_enabled_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> {
> int order = to_thpsize(kobj)->order;
> const char *output;
> @@ -500,9 +500,9 @@ static ssize_t thpsize_enabled_show(struct kobject *kobj,
> return sysfs_emit(buf, "%s\n", output);
> }
>
> -static ssize_t thpsize_enabled_store(struct kobject *kobj,
> - struct kobj_attribute *attr,
> - const char *buf, size_t count)
> +static ssize_t anon_enabled_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> {
> int order = to_thpsize(kobj)->order;
> ssize_t ret = count;
> @@ -544,19 +544,35 @@ static ssize_t thpsize_enabled_store(struct kobject *kobj,
> return ret;
> }
>
> -static struct kobj_attribute thpsize_enabled_attr =
> - __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store);
> +static struct kobj_attribute anon_enabled_attr =
> + __ATTR(enabled, 0644, anon_enabled_show, anon_enabled_store);
>
> -static struct attribute *thpsize_attrs[] = {
> - &thpsize_enabled_attr.attr,
> +static struct attribute *anon_ctrl_attrs[] = {
> + &anon_enabled_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group anon_ctrl_attr_grp = {
> + .attrs = anon_ctrl_attrs,
> +};
> +
> +static struct attribute *file_ctrl_attrs[] = {
> #ifdef CONFIG_SHMEM
> &thpsize_shmem_enabled_attr.attr,
> #endif
> NULL,
> };
>
> -static const struct attribute_group thpsize_attr_group = {
> - .attrs = thpsize_attrs,
> +static const struct attribute_group file_ctrl_attr_grp = {
> + .attrs = file_ctrl_attrs,
> +};
> +
> +static struct attribute *any_ctrl_attrs[] = {
> + NULL,
> +};
> +
> +static const struct attribute_group any_ctrl_attr_grp = {
> + .attrs = any_ctrl_attrs,
> };
I wonder why adding a NULL group?
>
> static const struct kobj_type thpsize_ktype = {
> @@ -595,64 +611,132 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
> DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
> DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
> +#ifdef CONFIG_SHMEM
> DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC);
> DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK);
> DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE);
> +#endif
> DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
> DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
> DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
>
> -static struct attribute *stats_attrs[] = {
> +static struct attribute *anon_stats_attrs[] = {
> &anon_fault_alloc_attr.attr,
> &anon_fault_fallback_attr.attr,
> &anon_fault_fallback_charge_attr.attr,
> +#ifndef CONFIG_SHMEM
> &swpout_attr.attr,
> &swpout_fallback_attr.attr,
> - &shmem_alloc_attr.attr,
> - &shmem_fallback_attr.attr,
> - &shmem_fallback_charge_attr.attr,
> +#endif
> &split_attr.attr,
> &split_failed_attr.attr,
> &split_deferred_attr.attr,
> NULL,
> };
>
> -static struct attribute_group stats_attr_group = {
> +static struct attribute_group anon_stats_attr_grp = {
> + .name = "stats",
> + .attrs = anon_stats_attrs,
> +};
> +
> +static struct attribute *file_stats_attrs[] = {
> +#ifdef CONFIG_SHMEM
> + &shmem_alloc_attr.attr,
> + &shmem_fallback_attr.attr,
> + &shmem_fallback_charge_attr.attr,
> +#endif
> + NULL,
> +};
> +
> +static struct attribute_group file_stats_attr_grp = {
> + .name = "stats",
> + .attrs = file_stats_attrs,
> +};
> +
> +static struct attribute *any_stats_attrs[] = {
> +#ifdef CONFIG_SHMEM
> + &swpout_attr.attr,
> + &swpout_fallback_attr.attr,
> +#endif
Sorry I did not point it out in early version. I think file pages and
shmem can also be split, while 'split_deferred' is only for anonymous
page. So I think the any_stats_attrs should be:
static struct attribute *any_stats_attrs[] = {
#ifdef CONFIG_SHMEM
&swpout_attr.attr,
&swpout_fallback_attr.attr,
#endif
&split_attr.attr,
&split_failed_attr.attr,
NULL,
};
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