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Shutemov" , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Andrea Arcangeli , David Rientjes , "Aneesh Kumar K.V" , swkhack , "Potyra, Stefan" , Mike Rapoport , Stephen Rothwell , Colin Ian King , Jason Gunthorpe , Mauro Carvalho Chehab , Peng Fan , Nikolay Borisov , Ira Weiny , Kirill Tkhai , Yafang Shao Subject: Re: [PATCH v3 3/7] mm/lru: replace pgdat lru_lock with lruvec lock Message-ID: <20191119021058.auxc6g7vmgf7d5gg@ca-dmjordan1.us.oracle.com> References: <1573874106-23802-1-git-send-email-alex.shi@linux.alibaba.com> <1573874106-23802-4-git-send-email-alex.shi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1573874106-23802-4-git-send-email-alex.shi@linux.alibaba.com> User-Agent: NeoMutt/20180716 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9445 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=575 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911190017 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9445 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=644 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911190017 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, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: > @@ -192,26 +190,17 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, > void *arg) > { > int i; > - struct pglist_data *pgdat = NULL; > - struct lruvec *lruvec; > - unsigned long flags = 0; > + struct lruvec *lruvec = NULL; > > for (i = 0; i < pagevec_count(pvec); i++) { > struct page *page = pvec->pages[i]; > - struct pglist_data *pagepgdat = page_pgdat(page); > > - if (pagepgdat != pgdat) { > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > - pgdat = pagepgdat; > - spin_lock_irqsave(&pgdat->lru_lock, flags); > - } > + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); > > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > (*move_fn)(page, lruvec, arg); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > } > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > + > release_pages(pvec->pages, pvec->nr); > pagevec_reinit(pvec); > } Why can't you keep the locking pattern where we only drop and reacquire if the lruvec changes? It'd save a lot of locks and unlocks if most pages were from the same memcg and node, or the memory controller were unused. Thanks for running the -readtwice benchmark, by the way.