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From: Ritesh Harjani <riteshh@linux.ibm.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>,
	Anju T Sudhakar <anju@linux.vnet.ibm.com>,
	darrick.wong@oracle.com, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	willy@infradead.org
Subject: Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend().
Date: Fri, 21 Aug 2020 14:39:33 +0530	[thread overview]
Message-ID: <20200821090934.4BDF04C04A@d06av22.portsmouth.uk.ibm.com> (raw)
In-Reply-To: <20200821060025.GA31091@infradead.org>



On 8/21/20 11:30 AM, Christoph Hellwig wrote:
> On Fri, Aug 21, 2020 at 10:15:33AM +0530, Ritesh Harjani wrote:
>> Please correct me here, but as I see, bio has only these two limits
>> which it checks for adding page to bio. It doesn't check for limits
>> of /sys/block/<dev>/queue/* no? I guess then it could be checked
>> by block layer below b4 submitting the bio?
> 
> The bio does not, but the blk-mq code will split the bios when mapping
> it to requests, take a look at blk_mq_submit_bio and __blk_queue_split.

Thanks :)

> 
> But while the default limits are quite low, they can be increased
> siginificantly, which tends to help with performance and is often
> also done by scripts shipped by the distributions.
> 
>> This issue was first observed while running a fio run on a system with
>> huge memory. But then here is an easy way we figured out to trigger the
>> issue almost everytime with loop device on my VM setup. I have provided
>> all the details on this below.
> 
> Can you wire this up for xfstests?
> 

Sure, will do that.
I do see generic/460 does play with such vm dirty_ratio params which
this test would also require to manipulate to trigger this issue.


Thanks for the suggestion!
-ritesh

  reply	other threads:[~2020-08-21  9:09 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 10:28 [PATCH] iomap: Fix the write_count in iomap_add_to_ioend() Anju T Sudhakar
2020-08-20 23:11 ` Dave Chinner
2020-08-21  4:45   ` Ritesh Harjani
2020-08-21  6:00     ` Christoph Hellwig
2020-08-21  9:09       ` Ritesh Harjani [this message]
2020-08-21 21:53     ` Dave Chinner
2020-08-22 13:13       ` Christoph Hellwig
2020-08-24 14:28         ` Brian Foster
2020-08-24 15:04           ` Christoph Hellwig
2020-08-24 15:48             ` Brian Foster
2020-08-25  0:42               ` Dave Chinner
2020-08-25 14:49                 ` Brian Foster
2020-08-31  4:01                   ` Ming Lei
2020-08-31 14:35                     ` Brian Foster
2020-09-16  0:12                   ` Darrick J. Wong
2020-09-16  8:45                     ` Christoph Hellwig
2020-09-16 13:07                       ` Brian Foster
2020-09-17  8:04                         ` Christoph Hellwig
2020-09-17 10:42                           ` Brian Foster
2020-09-17 14:48                             ` Christoph Hellwig
2020-09-17 21:33                               ` Darrick J. Wong
2020-09-17 23:13                           ` Ming Lei
2020-08-21  6:01   ` Christoph Hellwig
2020-08-21  6:07 ` Christoph Hellwig
2020-08-21  8:53   ` Ritesh Harjani
2020-08-21 14:49   ` Jens Axboe
2020-08-21 13:31 ` Matthew Wilcox

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