From: Joao Martins <joao.m.martins@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Linux NVDIMM <nvdimm@lists.linux.dev>,
linux-s390 <linux-s390@vger.kernel.org>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: can we finally kill off CONFIG_FS_DAX_LIMITED
Date: Tue, 24 Aug 2021 15:17:02 +0100 [thread overview]
Message-ID: <e3f49c83-2391-4a7e-6255-e4e577790983@oracle.com> (raw)
In-Reply-To: <CAPcyv4jpHX4U3XisqVoaMf_qADDzKyDS1wOijCs3JR_ByrXmHA@mail.gmail.com>
On 8/20/21 6:42 PM, Dan Williams wrote:
> On Fri, Aug 20, 2021 at 8:41 AM Dan Williams <dan.j.williams@intel.com> wrote:
>>
>> [ add Gerald and Joao ]
>>
>> On Thu, Aug 19, 2021 at 10:44 PM Christoph Hellwig <hch@lst.de> wrote:
>>>
>>> Hi all,
>>>
>>> looking at the recent ZONE_DEVICE related changes we still have a
>>> horrible maze of different code paths. I already suggested to
>>> depend on ARCH_HAS_PTE_SPECIAL for ZONE_DEVICE there, which all modern
>>> architectures have anyway. But the other odd special case is
>>> CONFIG_FS_DAX_LIMITED which is just used for the xpram driver. Does
>>> this driver still see use? If so can we make it behave like the
>>> other DAX drivers and require a pgmap? I think the biggest missing
>>> part would be to implement ARCH_HAS_PTE_DEVMAP for s390.
>>>
>>
>> Gerald,
>>
>> Might you still be looking to help dcssblk get out of FS_DAX_LIMITED
>> jail [1]? I recall Martin saying that 'struct page' overhead was
>> prohibitive. I don't know if Joao's 'struct page' diet patches could
>> help alleviate that at all (would require the filesystem to only
>> allocate blocks in large page sizes).
/me nods
Either that or dynamically remapping the deduplicated tail page vmemmap
areas when we punch holes in what was represented as a compound page (or
when we collapse pages back together). Not sure how crazy the latter is.
>>
>> [1]: https://lore.kernel.org/r/20180523205017.0f2bc83e@thinkpad
>
next prev parent reply other threads:[~2021-08-24 14:17 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 5:43 can we finally kill off CONFIG_FS_DAX_LIMITED Christoph Hellwig
2021-08-20 15:41 ` Dan Williams
2021-08-20 17:42 ` Dan Williams
2021-08-20 19:03 ` Gerald Schaefer
2021-08-24 14:17 ` Joao Martins [this message]
2021-08-23 14:05 ` Gerald Schaefer
2021-08-23 19:47 ` Gerald Schaefer
2021-08-23 20:21 ` Dan Williams
2021-08-24 14:09 ` Joao Martins
2021-08-24 14:53 ` Dan Williams
2021-08-24 18:24 ` Gerald Schaefer
2021-08-24 18:44 ` Dan Williams
2021-10-14 23:04 ` Jason Gunthorpe
2021-10-15 0:22 ` Joao Martins
2021-10-18 23:30 ` Jason Gunthorpe
2021-10-19 4:26 ` Dan Williams
2021-10-19 14:20 ` Jason Gunthorpe
2021-10-19 15:20 ` Joao Martins
2021-10-19 15:38 ` Felix Kuehling
2021-10-19 17:38 ` Dan Williams
2021-10-19 17:54 ` Jason Gunthorpe
2021-08-24 6:49 ` David Hildenbrand
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