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bh=b9/b7bE9KTxVxI9uuF80Hmje+jImq1gFOBY8r53F4LM=; b=Aq9GuSU4uk848Ao4sTVSe7AFwL g9vvyxRH60CSoA6TSxwPMmng2cVfGfrnr6a1ZkioaqHSGdccIytqckrLkRWdHqFX1znQuEdwU9OOT sP/uzBYc7RNweph2JeMlVtsWbE7Jcf+3MgXQtoZ2obNOQwlQ1ObPeXK5IXu6v6zMMQoQ=; Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.2) id 1jCZOV-00HMnE-A2 for linux-f2fs-devel@lists.sourceforge.net; Fri, 13 Mar 2020 01:45:51 +0000 Received: from localhost (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 00EFA206EB; Fri, 13 Mar 2020 01:45:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584063936; bh=eOeeLsiw73oz23MELGRqbWNabA9/QJa23yrnUToudVM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KpuV21MXLiAl8IdbIWtXwY3FgUU8dBbJ9WEo93Kwg+/GbAoFuNFGEfl/f/SaBxTIY be3GCDYZZlblAInUV8NiFetDEY4YfF/f0t23vKmPCD8pVdooMxCVlRIfLPmlZHLemP cvpyyBOHJc1NiUw1RwXDYvTCQbstB8PkklyaTh20= Date: Thu, 12 Mar 2020 18:45:35 -0700 From: Jaegeuk Kim To: Sahitya Tummala Message-ID: <20200313014535.GA72547@google.com> References: <1584011671-20939-1-git-send-email-stummala@codeaurora.org> <20200312170242.GA185506@google.com> <20200313012604.GI20234@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200313012604.GI20234@codeaurora.org> User-Agent: Mutt/1.12.2 (2019-09-21) X-Headers-End: 1jCZOV-00HMnE-A2 Subject: Re: [f2fs-dev] [PATCH] f2fs: fix long latency due to discard during umount X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 03/13, Sahitya Tummala wrote: > On Thu, Mar 12, 2020 at 10:02:42AM -0700, Jaegeuk Kim wrote: > > On 03/12, Sahitya Tummala wrote: > > > F2FS already has a default timeout of 5 secs for discards that > > > can be issued during umount, but it can take more than the 5 sec > > > timeout if the underlying UFS device queue is already full and there > > > are no more available free tags to be used. In that case, submit_bio() > > > will wait for the already queued discard requests to complete to get > > > a free tag, which can potentially take way more than 5 sec. > > > > > > Fix this by submitting the discard requests with REQ_NOWAIT > > > flags during umount. This will return -EAGAIN for UFS queue/tag full > > > scenario without waiting in the context of submit_bio(). The FS can > > > then handle these requests by retrying again within the stipulated > > > discard timeout period to avoid long latencies. > > > > > > Signed-off-by: Sahitya Tummala > > > --- > > > fs/f2fs/segment.c | 14 +++++++++++++- > > > 1 file changed, 13 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > > index fb3e531..a06bbac 100644 > > > --- a/fs/f2fs/segment.c > > > +++ b/fs/f2fs/segment.c > > > @@ -1124,10 +1124,13 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, > > > struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info; > > > struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ? > > > &(dcc->fstrim_list) : &(dcc->wait_list); > > > - int flag = dpolicy->sync ? REQ_SYNC : 0; > > > + int flag; > > > block_t lstart, start, len, total_len; > > > int err = 0; > > > > > > + flag = dpolicy->sync ? REQ_SYNC : 0; > > > + flag |= dpolicy->type == DPOLICY_UMOUNT ? REQ_NOWAIT : 0; > > > + > > > if (dc->state != D_PREP) > > > return 0; > > > > > > @@ -1203,6 +1206,11 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, > > > bio->bi_end_io = f2fs_submit_discard_endio; > > > bio->bi_opf |= flag; > > > submit_bio(bio); > > > + if ((flag & REQ_NOWAIT) && (dc->error == -EAGAIN)) { > > > + dc->state = D_PREP; > > > + err = dc->error; > > > + break; > > > + } > > > > > > atomic_inc(&dcc->issued_discard); > > > > > > @@ -1510,6 +1518,10 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > > > } > > > > > > __submit_discard_cmd(sbi, dpolicy, dc, &issued); > > > + if (dc->error == -EAGAIN) { > > > + congestion_wait(BLK_RW_ASYNC, HZ/50); > > > > --> need to be DEFAULT_IO_TIMEOUT > > Yes, i will update it. > > > > > > + __relocate_discard_cmd(dcc, dc); > > > > It seems we need to submit bio first, and then move dc to wait_list, if there's > > no error, in __submit_discard_cmd(). > > Yes, that is not changed and it still happens for the failed request > that is re-queued here too when it gets submitted again later. > > I am requeuing the discard request failed with -EAGAIN error back to > dcc->pend_list[] from wait_list. It will call submit_bio() for this request > and also move to wait_list when it calls __submit_discard_cmd() again next > time. Please let me know if I am missing anything? This patch has no problem, but I'm thinking that __submit_discard_cmd() needs to return with any values by assumption where the waiting list should have submitted commands. > > Thanks, > > > > > > + } > > > > > > if (issued >= dpolicy->max_requests) > > > break; > > > -- > > > Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. > > > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project. > > -- > -- > Sent by a consultant of the Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel