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From:   Andreas Dilger <adilger@dilger.ca>
Message-Id: <90D76828-C2EE-459A-A190-8E4FB51CE118@dilger.ca>
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Subject: Re: code questions about ext4_inode_datasync_dirty()
Date:   Mon, 18 Jan 2021 20:40:47 -0700
In-Reply-To: <20210113171943.GB26686@quack2.suse.cz>
Cc:     Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        joseph qi <joseph.qi@linux.alibaba.com>
To:     Jan Kara <jack@suse.cz>
References: <c95ac3d6-5e9c-b706-28f7-3bbe4b75964b@linux.alibaba.com>
 <20210113171943.GB26686@quack2.suse.cz>
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On Jan 13, 2021, at 10:19 AM, Jan Kara <jack@suse.cz> wrote:
> 
> Hi!
> 
> On Tue 12-01-21 19:45:06, Xiaoguang Wang wrote:
>> I use io_uring to evaluate ext4 randread performance(direct io), observed
>> obvious overhead in jbd2_transaction_committed():

I was going to ask about this - is the filesystem mounted with noatime or
relatime or lazytime?  Otherwise, it may be a lot of atime updates that are
causing all of this journal traffic in what _should_ be a read-only workload?

Cheers, Andreas


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