From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=115.124.30.132 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794538257; b=bOKeFw2jmvdwrYCB+3RwxSHyTBB3JEprXL24gW6fN/FOKcEIHGi+JNMCUKiueHHwvQpS d+pOMikj7DlnF2mFtzDIs46dwyuwDmWPDv4C8GFwuBNJkVTRz8Lekw/cuDvYiGJ1KmNmJ gvFxDRG4xEPkWZuR8wqYJoEFCHg+TtDh/WOw3CLbzAJzGXcT5PpnhCTo11zBXz/mE8l1r IzG35cFmauJ3yNkmj0k3J+Tcp2XHVBV/uhsFjpeUe6yvg5qo/X0RgfCekp0jOJcnCiz03 LY2YH0oFYEArhOjBxOT24OLjtK4m7F8Q6DOMYRlZuV7oDlhkPZd4mugWm1twBHY+Zzw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794538257; h=DMARC-Filter:DKIM-Signature:X-Alimail-AntiSpam:Received:Message-ID: Date:MIME-Version:User-Agent:Subject:To:Cc:References:From: In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=mVe5HwVBkXjfHvoljda/mJvecIfGagV1bTDZ+w25zss=; b=zAOhJefmkwE9Va/K2X3vxru61VvxvUeeNs8n37R5k2pCy0J0qbCzMUQPE50NBdc24Kyd fjzNC9AHHjtlMuN6dMTo10lsaJxcphgqIb/tfmwWaUbF1z9tD19IsdvADwjgT+GF8+Stn 30xlUKy33m/eQa1dTo19fQQb618DkUiTfbNb2QLm4IpvE5kx+Ib5XvZpL3SrUXVGwOH5a rhb0ZXAKH0dgi2FoQlL1gtmMFIQ5K6wr+9Xke9LhpNXeFYzuS+2usFFx10ubArOvnyuo2 SUofL5BORGnU6VoInRIl8k0ysErVhhMdNGfo6ofJ3MHYKbngIQYeHb5phn25wblI6rg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=E6sSJsVs; arc=none smtp.remote-ip=115.124.30.132 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A5E4606A32D for ; Fri, 13 Nov 2026 02:50:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2A5E4606A32D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=E6sSJsVs DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1794538253; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=mVe5HwVBkXjfHvoljda/mJvecIfGagV1bTDZ+w25zss=; b=E6sSJsVsEaCjwvnsQikzMaUEUv/36jSyAoGGqiZSCCxOte7j9oVLLsGbJZ/gaMLFeT5nY0Wf0u9MtzybAllv1xT5ip1U6KBnRcclvHka/p2yyk6YH76opVFWC8940oT9z7jCQLgrB1QGjz7yr6lhSA+8iTSshPrKKNosk1/jOPM= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045133197;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0XEdfmiI_1794538251; Received: from 30.74.144.124(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XEdfmiI_1794538251 cluster:ay36) by smtp.aliyun-inc.com; Fri, 13 Nov 2026 10:50:52 +0800 Message-ID: Date: Fri, 13 Nov 2026 10:50:51 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/mglru: yield the lru_lock earlier in fill/drain_evictable() To: Hui Zhu , Andrew Morton , Johannes Weiner , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hui Zhu References: <20261113020132.274013-1-hui.zhu@linux.dev> From: Baolin Wang In-Reply-To: <20261113020132.274013-1-hui.zhu@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/13/26 10:01 AM, Hui Zhu wrote: > From: Hui Zhu > > lru_gen_change_state() migrates folios in batches of up to > MAX_LRU_BATCH (4096) folios under lruvec_lock_irq(). A full batch > keeps local interrupts off for up to about a millisecond, and CPUs > contending for the same lru_lock spin with interrupts disabled for > that long. > > The caller already reschedules between batches, but a batch itself > only ends after 4096 folios. Stop it early when a resched is > pending, or when the lock has waiters and the current hold has moved > at least MIN_LRU_BATCH folios; the caller restarts where it left off. > TIF_NEED_RESCHED can still be set with interrupts off: a remote > resched_curr() sets it directly in the target's thread_info. The > minimum batch avoids lock bouncing under sustained contention, while > a waiter now waits ~15us instead of ~1ms. > > This follows lru_gen_look_around() in this file, security/keys/gc.c > and jbd2_log_do_checkpoint(), and commit 6e9be217a3ce ("mm/mglru: > use a smaller batch for reclaim"). > > Signed-off-by: Hui Zhu > --- > Changlog: > v2: > Also yield on lock contention after a minimum batch (Kairui Song). > > mm/vmscan.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 6a1af9b92349..c1231925159f 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -5533,7 +5533,10 @@ static bool fill_evictable(struct lruvec *lruvec) > success = lru_gen_add_folio(lruvec, folio, !active); > VM_WARN_ON_ONCE(!success); > > - if (!--remaining) > + /* stop early to shorten the irq-off section */ > + if (!--remaining || need_resched() || > + (MAX_LRU_BATCH - remaining >= MIN_LRU_BATCH && > + spin_is_contended(&lruvec->lru_lock))) > return false; IIUC, Kairui's point[1] is to just drop the 'MAX_LRU_BATCH - remaining >= MIN_LRU_BATCH' condition, no? if (!--remaining || need_resched() || spin_is_contended(&lruvec->lru_lock)) [1] https://lore.kernel.org/all/CAMgjq7CUMuNSdCXZ7_kDdo9+0BFvPNHuO=mq=ct_Q5YUyyckvQ@mail.gmail.com/