Re: [PATCHSET v6 0/12] Uncached buffered IO

Jens Axboe
2024-12-12T19:14:26Z

On 12/12/24 9:59 AM, Christoph Lameter (Ampere) wrote:
> On Thu, 12 Dec 2024, Jens Axboe wrote:
>
>> On 12/10/24 4:11 AM, Christoph Hellwig wrote:
>>> On Tue, Dec 03, 2024 at 09:52:41PM -0800, Darrick J. Wong wrote:
>>>> <shrug> RWF_DONTCACHE, to match {I,DCACHE}_DONTCACHE ? ;)
>>>>
>>>> They sound pretty similar ("load this so I can do something with it,
>>>> evict it immediately if possible") though I wouldn't rely on people
>>>> outside the kernel being familiar with the existing dontcaches.
>>>
>>> FYI, another word for dontcache. uncached just has too many conotations
>>> in the kernel context.
>>
>> Sure, we can go with DONTCACHE instead. Only thing I don't like about
>> that is that you can use uncached as a verb and adjective, eg talking
>> about uncached IO. Talking about dontcached IO sounds pretty weird.
>>
>> As I've said previously in this and other threads, I don't feel too
>> strongly about the in-kernel naming, I care more about the exposed
>> name. And uncached does seem to be the most descriptive and most
>> easily understandable by users.
>
> The page is cached while the operation is ongoing. "Transitory" would be
> more accurate and it is a new term that was not used with pages before.

Like I mentioned earlier, the fact that it's cached for the duration of
the operation is more of an implementation detail that developers need
not worry about. What's important is that it's not cached AFTER. I still
feel UNCACHED is the best description, but I'll change it to DONTCACHE
for the next version just to avoid the overlap with other in-kernel
uses.

--
Jens Axboe