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d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cHegjZcU0XOaLxA3426H5gnc8atFuiYj+6kFdWj5ljE=; b=G9Ts+vcTgWjkK/pM2wzbKCUbU0WSGP0fBDVKegDR59i+Zqq0V8NqREgwFcOBlo3Hin RSug5e0OAItKAvslPZ698EL3d7m2aU/dHX2JKUqOayKxYH2icSsjEn2Ub0lKWpgt22Xc XP7nwEDQBEjz8r9Z2mPzZ607bMs5lD6z+qOTGwl57CVlL/gfkkj0mjCT8CjySq/D84e0 3Wp6KEJXU9p5hm7TNbVtcDNF0xpc1vQHumTEVhrnzxKJ4Xg16T8Qn5nVO/EeMEM+gpLa AFi6zcVAVcow9PjtFo8ao1IcOzLjbRz30XBgvcwr2Jfp/ox0EdZlKQRECqZAv9yYFnJ/ /s0Q== X-Gm-Message-State: AOAM533gcMkruVWNwsKw4xrTzmUig/ye7NnNr7eCkIbvMzAMBcX+DcC1 oAGvZyOgcwNN2jG1U0pARuZABVYLbCtw2QvYeAI= X-Google-Smtp-Source: ABdhPJySR/ElNUPu/PRuA5+q877G96Zj8p+NIBqU+6fXRvhBw3ZZPj6G1VvyjexkX1gnKj4evN8mvAzRBGHG5aS5gxA= X-Received: by 2002:a92:6904:: with SMTP id e4mr702536ilc.83.1597371994666; Thu, 13 Aug 2020 19:26:34 -0700 (PDT) MIME-Version: 1.0 References: <1597368611-7631-1-git-send-email-zhaoyang.huang@unisoc.com> <20200814014355.GS17456@casper.infradead.org> <20200814020700.GT17456@casper.infradead.org> In-Reply-To: From: Zhaoyang Huang Date: Fri, 14 Aug 2020 10:26:23 +0800 Message-ID: Subject: Re: [PATCH] mm : update ra->ra_pages if it's NOT equal to bdi->ra_pages To: Matthew Wilcox Cc: Roman Gushchin , Andrew Morton , Zhaoyang Huang , "open list:MEMORY MANAGEMENT" , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 8E7E410038E2E X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Fri, Aug 14, 2020 at 10:20 AM Zhaoyang Huang wrote: > > On Fri, Aug 14, 2020 at 10:07 AM Matthew Wilcox wrote: > > > > On Fri, Aug 14, 2020 at 02:43:55AM +0100, Matthew Wilcox wrote: > > > On Fri, Aug 14, 2020 at 09:30:11AM +0800, Zhaoyang Huang wrote: > > > > file->f_ra->ra_pages will remain the initialized value since it opend, which may > > > > be NOT equal to bdi->ra_pages as the latter one is updated somehow(etc, > > > > echo xxx > /sys/block/dm/queue/read_ahead_kb).So sync ra->ra_pages to the > > > > updated value when sync read. > > > > > > It still ignores the work done by shrink_readahead_size_eio() > > > and fadvise(POSIX_FADV_SEQUENTIAL). > > > > ... by the way, if you're trying to update one particular file's readahead > > state, you can just call fadvise(POSIX_FADV_NORMAL) on it. > > > > If you want to update every open file's ra_pages by writing to sysfs, > > then just no. We don't do that. > No, What I want to fix is the file within one process's context keeps > using the initialized value when it is opened and not sync with new > value when bdi->ra_pages changes. So you mean it is just the desired behavior as having the opened file use the initialized value even if bdi->ra_pages changed via sysfs? > > > > You haven't said what problem you're facing, so I really can't be more > > helpful.