From: Michal Hocko <mhocko@kernel.org>
To: Arun KS <arunks@codeaurora.org>
Cc: kys@microsoft.com, haiyangz@microsoft.com,
sthemmin@microsoft.com, boris.ostrovsky@oracle.com,
jgross@suse.com, akpm@linux-foundation.org,
dan.j.williams@intel.com, vbabka@suse.cz, iamjoonsoo.kim@lge.com,
gregkh@linuxfoundation.org, osalvador@suse.de, malat@debian.org,
kirill.shutemov@linux.intel.com, jrdr.linux@gmail.com,
yasu.isimatu@gmail.com, mgorman@techsingularity.net,
aaron.lu@intel.com, devel@linuxdriverproject.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
xen-devel@lists.xenproject.org, vatsa@codeaurora.org,
vinmenon@codeaurora.org, getarunks@gmail.com
Subject: Re: [PATCH v5 2/2] mm/page_alloc: remove software prefetching in __free_pages_core
Date: Tue, 9 Oct 2018 11:30:37 +0200 [thread overview]
Message-ID: <20181009093037.GI8528@dhcp22.suse.cz> (raw)
In-Reply-To: <1538727006-5727-2-git-send-email-arunks@codeaurora.org>
On Fri 05-10-18 13:40:06, Arun KS wrote:
> They not only increase the code footprint, they actually make things
> slower rather than faster. Remove them as contemporary hardware doesn't
> need any hint.
I agree with the change but it is much better to add some numbers
whenever arguing about performance impact.
>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Arun KS <arunks@codeaurora.org>
> ---
> mm/page_alloc.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 7ab5274..90db431 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1258,14 +1258,10 @@ void __free_pages_core(struct page *page, unsigned int order)
> struct page *p = page;
> unsigned int loop;
>
> - prefetchw(p);
> - for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
> - prefetchw(p + 1);
> + for (loop = 0; loop < nr_pages ; loop++, p++) {
> __ClearPageReserved(p);
> set_page_count(p, 0);
> }
> - __ClearPageReserved(p);
> - set_page_count(p, 0);
>
> page_zone(page)->managed_pages += nr_pages;
> set_page_refcounted(page);
> --
> 1.9.1
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-10-09 9:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-05 8:10 [PATCH v5 1/2] memory_hotplug: Free pages as higher order Arun KS
2018-10-05 8:10 ` [PATCH v5 2/2] mm/page_alloc: remove software prefetching in __free_pages_core Arun KS
2018-10-09 9:30 ` Michal Hocko [this message]
2018-10-10 16:36 ` Vlastimil Babka
2018-10-08 7:34 ` [PATCH v5 1/2] memory_hotplug: Free pages as higher order Oscar Salvador
2018-10-09 9:29 ` Michal Hocko
2018-10-09 9:54 ` Arun KS
2018-10-09 11:06 ` Michal Hocko
2018-10-10 8:07 ` Oscar Salvador
2018-10-10 10:51 ` Arun KS
2018-10-10 11:01 ` Oscar Salvador
2018-10-10 15:30 ` Vlastimil Babka
2018-10-10 16:56 ` Arun KS
2018-10-10 17:33 ` Michal Hocko
2018-10-11 2:29 ` Arun KS
2018-10-11 7:55 ` Michal Hocko
2018-10-19 2:18 ` Andrew Morton
2018-10-19 8:07 ` Michal Hocko
2018-10-22 10:33 ` Arun KS
2018-11-05 9:42 ` Arun KS
2018-11-05 21:44 ` Andrew Morton
2018-11-06 5:31 ` Arun KS
2018-10-11 8:07 ` Vlastimil Babka
2018-10-11 8:15 ` Michal Hocko
2018-11-19 22:15 ` Wei Yang
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