lkml.org 
[lkml]   [2018]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 3/4] infiniband/mm: convert to the new put_user_page() call
From
Date
On 10/1/18 7:35 AM, Dennis Dalessandro wrote:
> On 9/28/2018 11:12 PM, John Hubbard wrote:
>> On 9/28/18 8:39 AM, Jason Gunthorpe wrote:
>>> On Thu, Sep 27, 2018 at 10:39:47PM -0700, john.hubbard@gmail.com wrote:
>>>> From: John Hubbard <jhubbard@nvidia.com>
>> [...]
>>>>
>>>> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
>>>> index a41792dbae1f..9430d697cb9f 100644
>>>> +++ b/drivers/infiniband/core/umem.c
>>>> @@ -60,7 +60,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
>>>>           page = sg_page(sg);
>>>>           if (!PageDirty(page) && umem->writable && dirty)
>>>>               set_page_dirty_lock(page);
>>>> -        put_page(page);
>>>> +        put_user_page(page);
>>>
>>> Would it make sense to have a release/put_user_pages_dirtied to absorb
>>> the set_page_dity pattern too? I notice in this patch there is some
>>> variety here, I wonder what is the right way?
>>>
>>> Also, I'm told this code here is a big performance bottleneck when the
>>> number of pages becomes very long (think >> GB of memory), so having a
>>> future path to use some kind of batching/threading sound great.
>>>
>>
>> Yes. And you asked for this the first time, too. Consistent! :) Sorry for
>> being slow to pick it up. It looks like there are several patterns, and
>> we have to support both set_page_dirty() and set_page_dirty_lock(). So
>> the best combination looks to be adding a few variations of
>> release_user_pages*(), but leaving put_user_page() alone, because it's
>> the "do it yourself" basic one. Scatter-gather will be stuck with that.
>>
>> Here's a differential patch with that, that shows a nice little cleanup in
>> a couple of IB places, and as you point out, it also provides the hooks for
>> performance upgrades (via batching) in the future.
>>
>> Does this API look about right?
>
> I'm on board with that and the changes to hfi1 and qib.
>
> Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>

Hi Dennis, thanks for the review!

I'll add those new routines in and send out a v2 soon, now that it appears, from
the recent discussion, that this aspect of the approach is still viable.


thanks,
--
John Hubbard
NVIDIA

\
 
 \ /
  Last update: 2018-10-03 07:41    [W:0.134 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site