From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: kbusch@kernel.org, linux-nvme@lists.infradead.org, hch@lst.de,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Subject: Re: [PATVH V5] nvme-core: use xarray for ctrl ns tracking
Date: Fri, 14 Aug 2020 08:57:11 +0200 [thread overview]
Message-ID: <20200814065711.GA2070@lst.de> (raw)
In-Reply-To: <4654370f-40b9-1b35-1e22-864e762c3001@grimberg.me>
On Thu, Aug 13, 2020 at 11:33:41PM -0700, Sagi Grimberg wrote:
>
>> This patch replaces the ctrl->namespaces tracking from linked list to
>> xarray for better ns-mgmt on the host side. For host side
>> nvme_find_get_ns() falls into the fast path for NVMeOF passthru target.
>> This allows us to have better performance for NVMeOF passthru backend
>> since XArray has shows better performance numbers over having
>> a combination of read-write semapore read + linked list in the
>> nvme_find_get_ns() to find namespace in I/O patch from nsid specified
>> in the nvme_rw_cmd.
>
> This patch scares me to be honest...
>
> We have such non-trivial synchronization paths for ns scanning, ns
> removal, quiescing, freezing, path handling... I'm not even sure
> how many tests we'll need to verify that nothing breaks here.
Yes, same concern here. That being said I have plans for this or
next merge window to fix a lot of crap in the block layer about
the bdev mutex to update the size, which should lead to major
simpliciations of the nvme ns scanning/removal path. But I'd much
rather sort that our first rather than touching this code now.
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next prev parent reply other threads:[~2020-08-14 6:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-14 2:16 [PATVH V5] nvme-core: use xarray for ctrl ns tracking Chaitanya Kulkarni
2020-08-14 6:33 ` Sagi Grimberg
2020-08-14 6:57 ` Christoph Hellwig [this message]
2020-08-15 2:59 ` Chaitanya Kulkarni
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