linux-kernel - Re: [PATCH v3 4/4] RDMA/umem: batch page unpin in __ib_umem

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Date:   Wed, 10 Feb 2021 19:17:34 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Joao Martins <joao.m.martins@...cle.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Doug Ledford <dledford@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v3 4/4] RDMA/umem: batch page unpin in __ib_umem_release()

On Fri, Feb 05, 2021 at 08:41:27PM +0000, Joao Martins wrote:
> Use the newly added unpin_user_page_range_dirty_lock()
> for more quickly unpinning a consecutive range of pages
> represented as compound pages. This will also calculate
> number of pages to unpin (for the tail pages which matching
> head page) and thus batch the refcount update.
> 
> Running a test program which calls mr reg/unreg on a 1G in size
> and measures cost of both operations together (in a guest using rxe)
> with THP and hugetlbfs:
> 
> Before:
> 590 rounds in 5.003 sec: 8480.335 usec / round
> 6898 rounds in 60.001 sec: 8698.367 usec / round
> 
> After:
> 2688 rounds in 5.002 sec: 1860.786 usec / round
> 32517 rounds in 60.001 sec: 1845.225 usec / round
> 
> Signed-off-by: Joao Martins <joao.m.martins@...cle.com>
> ---
>  drivers/infiniband/core/umem.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

Would best for this to go through Andrew's tree

Acked-by: Jason Gunthorpe <jgg@...dia.com>

4x improvement is pretty good!

Jason