From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6A32C6FD18 for ; Tue, 28 Mar 2023 14:20:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230331AbjC1OUI (ORCPT ); Tue, 28 Mar 2023 10:20:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229556AbjC1OUH (ORCPT ); Tue, 28 Mar 2023 10:20:07 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7356198 for ; Tue, 28 Mar 2023 07:19:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680013160; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=f/m5SehYf6RbF0mCNKIuKWpkgQ5bnk3BT8O942PeKag=; b=chfRJlWfHMdarwszvcGNJHyzNowQVKtNsO+pr9sBEdbz5lcnYI/4gnIYA5GttIX70QFgdH 2pV9AWfRin11gCYksUKjy3rdZvkdgZVwVAynaKXihml7/qSkoP7uPEFR9AQrCIYscC9CWs dwm06Ah/pwh0ZqOOWVHVjhuUlPYcQWk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-159-_y0_tW6pN42bkhsN1F0pfg-1; Tue, 28 Mar 2023 10:19:16 -0400 X-MC-Unique: _y0_tW6pN42bkhsN1F0pfg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A076E848B68; Tue, 28 Mar 2023 14:19:07 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9DD891121330; Tue, 28 Mar 2023 14:19:06 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20230111052515.53941-5-zhujia.zj@bytedance.com> References: <20230111052515.53941-5-zhujia.zj@bytedance.com> <20230111052515.53941-1-zhujia.zj@bytedance.com> To: Jia Zhu Cc: dhowells@redhat.com, linux-cachefs@redhat.com, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Xin Yin , Jingbo Xu Subject: Re: [PATCH V4 4/5] cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <133077.1680013145.1@warthog.procyon.org.uk> Date: Tue, 28 Mar 2023 15:19:05 +0100 Message-ID: <133078.1680013145@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Jia Zhu wrote: > + if (!xa_empty(xa)) { > + xa_lock(xa); > + xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) { > + if (!cachefiles_ondemand_is_reopening_read(req)) { > + mask |= EPOLLIN; > + break; > + } > + } > + xa_unlock(xa); > + } I wonder if there's a more efficient way to do this. I guess it depends on how many reqs you expect to get in a queue. It might be worth taking the rcu_read_lock before calling xa_lock() and holding it over the whole loop. David