Re: [PATCHSET 0/5] Enable alloc caching and batched freeing for passthrough

Jens Axboe
2022-09-23T15:23:00Z

On 9/23/22 9:21 AM, Christoph Hellwig wrote:
> On Fri, Sep 23, 2022 at 09:19:15AM -0600, Jens Axboe wrote:
>> On 9/23/22 9:16 AM, Christoph Hellwig wrote:
>>> On Thu, Sep 22, 2022 at 12:28:00PM -0600, Jens Axboe wrote:
>>>> This is good for a 10% improvement for passthrough performance. For
>>>> a non-drive limited test case, passthrough IO is now more efficient
>>>> than the regular bdev O_DIRECT path.
>>>
>>> How so? If it ends up faster we are doing something wrong in the
>>> normal path as there should be no fundamental difference in the work
>>> that is being done.
>>
>> There's no fundamental difference, but the bdev path is more involved
>> than the simple passthrough path.
>
> Well, I guess that means there is some more fat we need to trim
> then..

Yes and no, there's always more fat to trim. But some of it is
inevitable, so...

--
Jens Axboe