[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <YxgXd0Z+cqRk7Y7U@localhost.localdomain>
Date: Wed, 7 Sep 2022 06:00:55 +0200
From: Oscar Salvador <osalvador@...e.de>
To: Marco Elver <elver@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Michal Hocko <mhocko@...e.com>,
Vlastimil Babka <vbabka@...e.cz>,
Eric Dumazet <edumazet@...gle.com>,
Waiman Long <longman@...hat.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>
Subject: Re: [PATCH v2 2/3] mm, page_owner: Add page_owner_stacks file to
print out only stacks and their counter
On Tue, Sep 06, 2022 at 10:35:00AM +0200, Marco Elver wrote:
> I think it's clear from the fact we're using the stack depot that any
> printing will print stacks. To mirror the existing
> 'stack_depot_print()', I'd go with 'stack_depot_print_all_count()'.
Fair enough, I will rename it then.
> Moderately better, but still not great. Essentially you need 2
> cursors, but with loff_t you only get 1.
>
> I think the loff_t parameter can be used to encode both cursors. In
> the kernel, loff_t is always 'long long', so it'll always be 64-bit.
>
> Let's assume that collisions in the hash table are rare, so the number
> of stacks per bucket are typically small. Then you can encode the
> index into the bucket in bits 0-31 and the bucket index in bits 32-63.
> STACK_HASH_ORDER_MAX is 20, so 32 bits is plenty to encode the index.
I see, I didn't think of it to be honest.
Then, the below (completely untested) should the trick:
<----
int stack_depot_print_all_count(char *buf, size_t size, loff_t *pos)
{
int ret = 0, stack_i, table_i;
struct stack_record **stacks, *stack;
unsigned long stack_table_entries = stack_hash_mask + 1;
stack_i = (*pos & 31);
table_i = (*pos >> 32);
new_table:
stacks = &stack_table[table_i];
stack = ((struct stack_record *)stacks) + stack_i;
for (; stack; stack = stack->next, stack_i++) {
if (!stack->size || stack->size < 0 ||
stack->size > size || stack->handle.valid != 1 ||
refcount_read(&stack->count) < 1)
continue;
ret += stack_trace_snprint(buf, size, stack->entries, stack->size, 0);
ret += scnprintf(buf + ret, size - ret, "stack count: %d\n\n",
refcount_read(&stack->count));
*pos |= stack_i;
*pos |= ((long long)table_i << 32);
return ret;
}
table_i++;
/* Keep looking all tables for valid stacks */
if (table_i < stack_table_entries)
goto new_table;
return 0;
}
---->
I will give it a go.
Thanks Marco!
--
Oscar Salvador
SUSE Labs
Powered by blists - more mailing lists