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Shutemov" To: Hillf Danton Cc: linux-mm , Andrew Morton , linux-kernel , Matthew Wilcox , Michal Hocko , Johannes Weiner , Shakeel Butt , Minchan Kim , Mel Gorman , Vladimir Davydov , Jan Kara Subject: Re: [RFC v2] mm: add page preemption Message-ID: <20191028122609.k5suvp7b57oxglvj@box> References: <20191026112808.14268-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191026112808.14268-1-hdanton@sina.com> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Oct 26, 2019 at 07:28:08PM +0800, Hillf Danton wrote: > @@ -218,6 +219,9 @@ struct page { > > #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS > int _last_cpupid; > +#else > + int prio; > +#define CONFIG_PAGE_PREEMPTION PP > #endif > } _struct_page_alignment; > No. There's a really good reason we trying hard to push the _last_cpuid into page flags instead of growing the struct page by 4 bytes. I don't think your feature worth 0.1% of RAM and a lot of cache misses that this change would generate. -- Kirill A. Shutemov