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@xxxxxxxxx wrote: >>>> From: John Hubbard <jhubbard@xxxxxxxxxx> >> [...] >>>> >>>> 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@xxxxxxxxx> 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
