From: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To: Keith Busch <kbusch@kernel.org>
Cc: "hch@lst.de" <hch@lst.de>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"sagi@grimberg.me" <sagi@grimberg.me>
Subject: Re: [PATCH V2 1/2] nvme-core: replace ctrl page size with a macro
Date: Sat, 11 Jul 2020 18:20:26 +0000 [thread overview]
Message-ID: <BYAPR04MB49657BC0911F0E802C1E516D86620@BYAPR04MB4965.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20200710145742.GA2424089@dhcp-10-100-145-180.wdl.wdc.com
On 7/10/20 07:57, Keith Busch wrote:
> This makes it sound like we'd actually trigger this bug, but we
> currently don't do that. I think the changelog should be more about why
> we can remove of 'ctrl->page_size', something like:
>
> Saving the nvme controller's page size was from a time when the driver
> tried to use different sized pages, but this value is always set to
> a constant, and has been this way for some time. Remove the
> 'page_size' field and replace its usage with the constant value.
>
> This also lets the compiler make some micro-optimizations in the io
> path, and that's always a good thing.
>
Sure, I felt since it is not triggered yet it make sense to document
what actually might happen due to current code.
I'll use you log.
>
>> @@ -1825,7 +1824,7 @@ static int nvme_set_host_mem(struct nvme_dev *dev, u32 bits)
>> c.features.fid = cpu_to_le32(NVME_FEAT_HOST_MEM_BUF);
>> c.features.dword11 = cpu_to_le32(bits);
>> c.features.dword12 = cpu_to_le32(dev->host_mem_size >>
>> - ilog2(dev->ctrl.page_size));
>> + ilog2(NVME_CTRL_PAGE_SIZE));
> You could replace the ilog2() with NVME_CTRL_PAGE_SHIFT. Both compile to
> the same result, though.
>
Make sense.
I'll send V3 shortly.
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next prev parent reply other threads:[~2020-07-11 18:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 23:40 [PATCH V2 0/2] nvme: fix iod size calculation in nvme_probe() Chaitanya Kulkarni
2020-07-09 23:40 ` [PATCH V2 1/2] nvme-core: replace ctrl page size with a macro Chaitanya Kulkarni
2020-07-10 14:57 ` Keith Busch
2020-07-11 18:20 ` Chaitanya Kulkarni [this message]
2020-07-13 7:42 ` Christoph Hellwig
2020-07-14 0:02 ` Chaitanya Kulkarni
2020-07-14 16:44 ` Keith Busch
2020-07-09 23:40 ` [PATCH V2 2/2] nvme-pci: use max of PRP or SGL for iod size Chaitanya Kulkarni
2020-07-13 7:42 ` Christoph Hellwig
2020-07-13 23:59 ` Chaitanya Kulkarni
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