From: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
To: linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: disable mount with both dioread_nolock and nodelalloc
Date: Mon, 2 Sep 2019 09:31:23 +0800 [thread overview]
Message-ID: <12533d10-22e4-59bc-c7db-4c7ca5c2df69@linux.alibaba.com> (raw)
In-Reply-To: <20190731130600.7867-1-xiaoguang.wang@linux.alibaba.com>
hi,
Ping.
For this patch, I'm afraid someone else still takes effort to look into this issue.
Regards,
Xiaoguang Wang
> Mount with both dioread_nolock and nodelalloc will result in huge
> performance drop, which indeed is an known issue, so before we fix
> this issue, currently we disable this behaviour. Below test reproducer
> can reveal this performance drop.
>
> mount -o remount,dioread_nolock,delalloc /dev/vdb1
> rm -f testfile
> start_time=$(date +%s)
> dd if=/dev/zero of=testfile bs=4096 count=$((1024*256))
> sync
> end_time=$(date +%s)
> echo $((end_time - start_time))
>
> mount -o remount,dioread_nolock,nodelalloc /dev/vdb1
> rm -f testfile
> start_time=$(date +%s)
> dd if=/dev/zero of=testfile bs=4096 count=$((1024*256))
> sync
> end_time=$(date +%s)
> echo $((end_time - start_time))
>
> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
> ---
> fs/ext4/super.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 4079605d437a..1a2b2c0cd1b8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2098,6 +2098,12 @@ static int parse_options(char *options, struct super_block *sb,
> int blocksize =
> BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>
> + if (!test_opt(sb, DELALLOC)) {
> + ext4_msg(sb, KERN_ERR, "can't mount with "
> + "both dioread_nolock and nodelalloc");
> + return 0;
> + }
> +
> if (blocksize < PAGE_SIZE) {
> ext4_msg(sb, KERN_ERR, "can't mount with "
> "dioread_nolock if block size != PAGE_SIZE");
>
next prev parent reply other threads:[~2019-09-02 1:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 13:06 [PATCH] ext4: disable mount with both dioread_nolock and nodelalloc Xiaoguang Wang
2019-08-01 1:57 ` Joseph Qi
2019-09-02 1:31 ` Xiaoguang Wang [this message]
2019-09-07 16:00 ` Theodore Y. Ts'o
2019-09-09 3:40 ` Xiaoguang Wang
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