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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1597549677-7480-1-git-send-email-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.08.20 05:47, Alex Shi wrote: > pageblock_flags is used as long, since every pageblock_flags is just 4 > bits, 'long' size will include 8(32bit machine) or 16 pageblocks' flags, > that flag setting has to sync in cmpxchg with 7 or 15 other pageblock > flags. It would cause long waiting for sync. > > If we could change the pageblock_flags variable as char, we could use > char size cmpxchg, which just sync up with 2 pageblock flags. it could > relief much false sharing in cmpxchg. Do you have any performance numbers to back your claims? IOW, do we care at all? -- Thanks, David / dhildenb