From: Roman Gushchin <roman.gushchin@linux.dev>
To: "zhaoyang.huang" <zhaoyang.huang@unisoc.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Zhaoyang Huang <huangzhaoyang@gmail.com>,
ke.wang@unisoc.com
Subject: Re: [PATCH] mm: optimization on page allocation when CMA enabled
Date: Mon, 1 May 2023 10:12:07 -0700 [thread overview]
Message-ID: <ZE/y5wMggipQrKvb@P9FQF9L96D> (raw)
In-Reply-To: <1682679641-13652-1-git-send-email-zhaoyang.huang@unisoc.com>
Hi Zhaoyang!
On Fri, Apr 28, 2023 at 07:00:41PM +0800, zhaoyang.huang wrote:
> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
>
> Please be notice bellowing typical scenario that commit 168676649 introduce,
> that is, 12MB free cma pages 'help' GFP_MOVABLE to keep draining/fragmenting
> U&R page blocks until they shrink to 12MB without enter slowpath which against
> current reclaiming policy. This commit change the criteria from hard coded '1/2'
> to watermark check which leave U&R free pages stay around WMARK_LOW when being
> fallback.
Can you, please, explain the problem you're solving in more details?
If I understand your code correctly, you're effectively reducing the
use of cma areas for movable allocations. Why it's good?
Also, this is a hot path, please, make sure you're not adding
much overhead.
And please use scripts/checkpatch.pl next time, there are many
code style issues.
Thanks!
>
> DMA32 free:25900kB boost:0kB min:4176kB low:25856kB high:29516kB
>
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> ---
> mm/page_alloc.c | 40 ++++++++++++++++++++++++++++++++++++----
> 1 file changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0745aed..97768fe 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3071,6 +3071,39 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
>
> }
>
> +#ifdef CONFIG_CMA
> +static bool __if_use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
> +{
> + unsigned long cma_proportion = 0;
> + unsigned long cma_free_proportion = 0;
> + unsigned long watermark = 0;
> + unsigned long wm_fact[ALLOC_WMARK_MASK] = {1, 1, 2};
> + long count = 0;
> + bool cma_first = false;
> +
> + watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
> + /*check if GFP_MOVABLE pass previous watermark check via the help of CMA*/
> + if (!zone_watermark_ok(zone, order, watermark, 0, alloc_flags & (~ALLOC_CMA)))
> + {
> + alloc_flags &= ALLOC_WMARK_MASK;
> + /* WMARK_LOW failed lead to using cma first, this helps U&R stay
> + * around low when being drained by GFP_MOVABLE
> + */
> + if (alloc_flags <= ALLOC_WMARK_LOW)
> + cma_first = true;
> + /*check proportion for WMARK_HIGH*/
> + else {
> + count = atomic_long_read(&zone->managed_pages);
> + cma_proportion = zone->cma_pages * 100 / count;
> + cma_free_proportion = zone_page_state(zone, NR_FREE_CMA_PAGES) * 100
> + / zone_page_state(zone, NR_FREE_PAGES);
> + cma_first = (cma_free_proportion >= wm_fact[alloc_flags] * cma_proportion
> + || cma_free_proportion >= 50);
> + }
> + }
> + return cma_first;
> +}
> +#endif
> /*
> * Do the hard work of removing an element from the buddy allocator.
> * Call me with the zone->lock already held.
> @@ -3087,10 +3120,9 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
> * allocating from CMA when over half of the zone's free memory
> * is in the CMA area.
> */
> - if (alloc_flags & ALLOC_CMA &&
> - zone_page_state(zone, NR_FREE_CMA_PAGES) >
> - zone_page_state(zone, NR_FREE_PAGES) / 2) {
> - page = __rmqueue_cma_fallback(zone, order);
> + if (migratetype == MIGRATE_MOVABLE) {
> + bool cma_first = __if_use_cma_first(zone, order, alloc_flags);
> + page = cma_first ? __rmqueue_cma_fallback(zone, order) : NULL;
> if (page)
> return page;
> }
> --
> 1.9.1
>
>
next prev parent reply other threads:[~2023-05-01 17:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 11:00 [PATCH] mm: optimization on page allocation when CMA enabled zhaoyang.huang
2023-04-28 14:05 ` kernel test robot
2023-04-28 14:16 ` kernel test robot
2023-05-01 17:12 ` Roman Gushchin [this message]
2023-05-02 12:12 ` 答复: " 黄朝阳 (Zhaoyang Huang)
2023-05-02 22:01 ` Roman Gushchin
2023-05-03 7:58 ` Zhaoyang Huang
2023-05-03 16:30 ` Roman Gushchin
2023-05-04 6:23 ` Zhaoyang Huang
2023-05-04 6:30 ` Zhaoyang Huang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZE/y5wMggipQrKvb@P9FQF9L96D \
--to=roman.gushchin@linux.dev \
--cc=akpm@linux-foundation.org \
--cc=guro@fb.com \
--cc=huangzhaoyang@gmail.com \
--cc=ke.wang@unisoc.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=zhaoyang.huang@unisoc.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).