linux-kernel - Re: XFS mounted with 'discard' option

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Date:   Sun, 10 Sep 2017 23:42:37 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Hao Chen <haochen@...zon.com>
Cc:     "Lu, Qian" <luqia@...zon.com>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
        "darrick.wong@...cle.com" <darrick.wong@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        amazon-linux-kernel <amazon-linux-kernel@...zon.com>
Subject: Re: XFS mounted with 'discard' option - deleting fio test files slow

On Fri, Sep 08, 2017 at 04:21:52PM -0700, Hao Chen wrote:
> This is expected.  To get a better performance of XFS on NVMe drive, it
> is advised not use use the realtime discard option.
> 
> https://www.intel.com/content/dam/support/us/en/documents/ssdc/data-center-ssds/Intel_Linux_NVMe_Guide_330602-002.pdf

Again, this will depend on your device.  Intel in particular was the
example in my presentation for horrible performance of the NVMe
discard support - other vendors implement much better discard support,
so you'll see much better results.