* fs_dax_get_by_host in the hot path
@ 2017-08-24 13:45 Christoph Hellwig
2017-08-24 14:48 ` Dan Williams
0 siblings, 1 reply; 3+ messages in thread
From: Christoph Hellwig @ 2017-08-24 13:45 UTC (permalink / raw)
To: Dan Williams; +Cc: linux-nvdimm, linux-fsdevel
Hi Dan,
I just noticed that we now do a fs_dax_get_by_host in every
iomap_begin call for DAX. This function iterates a list,
does a string compared and igrab. I really think we need
to cache this in the superblock (possible even the fs
superblock) similar to what we do for the block device.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: fs_dax_get_by_host in the hot path
2017-08-24 13:45 fs_dax_get_by_host in the hot path Christoph Hellwig
@ 2017-08-24 14:48 ` Dan Williams
2017-08-24 15:19 ` Christoph Hellwig
0 siblings, 1 reply; 3+ messages in thread
From: Dan Williams @ 2017-08-24 14:48 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-nvdimm@lists.01.org, linux-fsdevel
On Thu, Aug 24, 2017 at 6:45 AM, Christoph Hellwig <hch@lst.de> wrote:
> Hi Dan,
>
> I just noticed that we now do a fs_dax_get_by_host in every
> iomap_begin call for DAX. This function iterates a list,
> does a string compared and igrab. I really think we need
> to cache this in the superblock (possible even the fs
> superblock) similar to what we do for the block device.
Sure, I'll get that fixed up. I believe I arrived at this scheme as a
side-effect / misunderstanding of this comment:
https://groups.google.com/d/msg/linux.kernel/9ho8SFe6RSw/6zTgNaNTCgAJ
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: fs_dax_get_by_host in the hot path
2017-08-24 14:48 ` Dan Williams
@ 2017-08-24 15:19 ` Christoph Hellwig
0 siblings, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2017-08-24 15:19 UTC (permalink / raw)
To: Dan Williams; +Cc: Christoph Hellwig, linux-nvdimm@lists.01.org, linux-fsdevel
On Thu, Aug 24, 2017 at 07:48:18AM -0700, Dan Williams wrote:
> Sure, I'll get that fixed up. I believe I arrived at this scheme as a
> side-effect / misunderstanding of this comment:
>
> https://groups.google.com/d/msg/linux.kernel/9ho8SFe6RSw/6zTgNaNTCgAJ
The current scheme is doing the right thing in terms of returning
the dax device from ->iomap_begin. But it still do so efficiently :)
^ permalink raw reply [flat|nested] 3+ messages in thread
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