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Message-ID: <14823123-79e3-4c7d-8501-8c46c6ec13c7@arm.com>
Date: Mon, 2 Sep 2024 10:58:22 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Baolin Wang <baolin.wang@...ux.alibaba.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
Hi Baolin,
Thanks for the review - I've been out on Paternity leave so only getting around
to replying now...
On 09/08/2024 09:31, Baolin Wang wrote:
>
>
> 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?
It made everything a bit more generic and therefore extensible. Its my
preference to leave it as is, but will remove it if you insist.
>
>> 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,
> };
Ahh yes, good point. I'll fix this in the next version (I'm back in office on
Wednesday so will send it then).
Thanks,
Ryan
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