Re: [PATCH v2 0/6] RFC: gup+dma: tracking dma-pinned pages

John Hubbard
2018-11-30T03:00:27Z

On 11/29/18 6:30 PM, Tom Talpey wrote:
> On 11/29/2018 9:21 PM, John Hubbard wrote:
>> On 11/29/18 6:18 PM, Tom Talpey wrote:
>>> On 11/29/2018 8:39 PM, John Hubbard wrote:
>>>> On 11/28/18 5:59 AM, Tom Talpey wrote:
>>>>> On 11/27/2018 9:52 PM, John Hubbard wrote:
>>>>>> On 11/27/18 5:21 PM, Tom Talpey wrote:
>>>>>>> On 11/21/2018 5:06 PM, John Hubbard wrote:
>>>>>>>> On 11/21/18 8:49 AM, Tom Talpey wrote:
>>>>>>>>> On 11/21/2018 1:09 AM, John Hubbard wrote:
>>>>>>>>>> On 11/19/18 10:57 AM, Tom Talpey wrote:
>>>>>> [...]
>>> Excerpting from below:
>>>
>>>> Baseline 4.20.0-rc3 (commit f2ce1065e767), as before:
>>>>       read: IOPS=193k, BW=753MiB/s (790MB/s)(1024MiB/1360msec)
>>>>      cpu          : usr=16.26%, sys=48.05%, ctx=251258, majf=0, minf=73
>>>
>>> vs
>>>
>>>> With patches applied:
>>>>       read: IOPS=193k, BW=753MiB/s (790MB/s)(1024MiB/1360msec)
>>>>      cpu          : usr=16.26%, sys=48.05%, ctx=251258, majf=0, minf=73
>>>
>>> Perfect results, not CPU limited, and full IOPS.
>>>
>>> Curiously identical, so I trust you've checked that you measured
>>> both targets, but if so, I say it's good.
>>>
>>
>> Argh, copy-paste error in the email. The real "before" is ever so slightly
>> better, at 194K IOPS and 759 MB/s:
>
> Definitely better - note the system CPU is lower, which is probably the
> reason for the increased IOPS.
>
>>    cpu          : usr=18.24%, sys=44.77%, ctx=251527, majf=0, minf=73
>
> Good result - a correct implementation, and faster.
>

Thanks, Tom, I really appreciate your experience and help on what performance
should look like here. (I'm sure you can guess that this is the first time
I've worked with fio, heh.)

I'll send out a new, non-RFC patchset soon, then.

thanks,
--
John Hubbard
NVIDIA