From: Christoph Hellwig <hch@lst.de>
To: Leon Romanovsky <leon@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Maor Gottlieb <maorg@nvidia.com>,
linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH rdma-next 4/4] RDMA/umem: Move to allocate SG table from pages
Date: Mon, 7 Sep 2020 09:29:26 +0200 [thread overview]
Message-ID: <20200907072926.GD19875@lst.de> (raw)
In-Reply-To: <20200903121853.1145976-5-leon@kernel.org>
On Thu, Sep 03, 2020 at 03:18:53PM +0300, Leon Romanovsky wrote:
> From: Maor Gottlieb <maorg@nvidia.com>
>
> Remove the implementation of ib_umem_add_sg_table and instead
> call to sg_alloc_table_append which already has the logic to
> merge contiguous pages.
>
> Besides that it removes duplicated functionality, it reduces the
> memory consumption of the SG table significantly. Prior to this
> patch, the SG table was allocated in advance regardless consideration
> of contiguous pages.
>
> In huge pages system of 2MB page size, without this change, the SG table
> would contain x512 SG entries.
> E.g. for 100GB memory registration:
>
> Number of entries Size
> Before 26214400 600.0MB
> After 51200 1.2MB
>
> Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Looks sensible for now, but the real fix is of course to avoid
the scatterlist here entirely, and provide a bvec based
pin_user_pages_fast. I'll need to finally get that done..
next prev parent reply other threads:[~2020-09-07 7:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 12:18 [PATCH rdma-next 0/4] scatterlist: add sg_alloc_table_append function Leon Romanovsky
2020-09-03 12:18 ` [PATCH rdma-next 2/4] lib/scatterlist: Add support in dynamically allocation of SG entries Leon Romanovsky
2020-09-07 7:29 ` Christoph Hellwig
2020-09-07 12:34 ` Maor Gottlieb
2020-09-03 12:18 ` [PATCH rdma-next 3/4] lib/scatterlist: Add support in dynamic allocation of SG table from pages Leon Romanovsky
2020-09-07 7:29 ` Christoph Hellwig
2020-09-07 12:44 ` Maor Gottlieb
2020-09-08 15:54 ` Christoph Hellwig
2020-09-08 16:13 ` Jason Gunthorpe
2020-09-03 12:18 ` [PATCH rdma-next 4/4] RDMA/umem: Move to allocate " Leon Romanovsky
2020-09-07 7:29 ` Christoph Hellwig [this message]
2020-09-08 14:10 ` Jason Gunthorpe
2020-09-03 15:32 ` [PATCH rdma-next 0/4] scatterlist: add sg_alloc_table_append function Christoph Hellwig
2020-09-03 15:55 ` Leon Romanovsky
2020-09-03 15:54 ` [PATCH rdma-next 1/4] lib/scatterlist: Refactor sg_alloc_table_from_pages Leon Romanovsky
2020-09-07 7:29 ` Christoph Hellwig
2020-09-07 12:32 ` Maor Gottlieb
2020-09-08 15:52 ` Christoph Hellwig
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