From: Jason Gunthorpe <jgg@ziepe.ca>
To: doug@easyco.com
Cc: Sagi Grimberg <sagi@grimberg.me>,
linux-rdma@vger.kernel.org, Max Gurtovoy <maxg@mellanox.com>,
Stephen Rust <srust@blockbridge.com>,
ming Lei <ming.lei@redhat.com>
Subject: Re: [PATCH] IB/isert: fix unaligned immediate-data handling
Date: Mon, 31 Aug 2020 14:59:31 -0300 [thread overview]
Message-ID: <20200831175931.GC24045@ziepe.ca> (raw)
In-Reply-To: <CAFx4rwRQ7z+sATpKuYNwTWqnepcWQeinxFjsZEEDAQobeSVACQ@mail.gmail.com>
On Mon, Aug 31, 2020 at 10:02:15AM -0700, Doug Dumitru wrote:
> On Mon, Aug 31, 2020 at 9:48 AM Sagi Grimberg <sagi@grimberg.me> wrote:
> >
> >
> > >> Currently we allocate rx buffers in a single contiguous buffers
> > >> for headers (iser and iscsi) and data trailer. This means
> > >> that most likely the data starting offset is aligned to 76
> > >> bytes (size of both headers).
> > >>
> > >> This worked fine for years, but at some point this broke.
> > >> To fix this, we should avoid passing unaligned buffers for
> > >> I/O.
> > >
> > > That is a bit vauge - what suddenly broke it?
> >
> > Somewhere around the multipage bvec work that Ming did. The issue was
> > that brd assumed a 512 aligned page vector. IIRC the discussion settled
> > that the block layer expects a 512B aligned buffer(s).
>
> I will second that block layers expect "at least" 512B aligned
> buffers. Many of them get less efficient when bvecs are not full, 4K
> aligned, pages.
Can we put all this info in the commit message please?
Thanks,
Jason
next prev parent reply other threads:[~2020-08-31 17:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-30 10:32 [PATCH] IB/isert: fix unaligned immediate-data handling Sagi Grimberg
2020-08-31 5:14 ` Christoph Hellwig
2020-08-31 5:37 ` Doug Dumitru
2020-08-31 12:18 ` Jason Gunthorpe
2020-08-31 16:29 ` Doug Dumitru
2020-08-31 16:48 ` Sagi Grimberg
[not found] ` <CAAFE1bcXNdMD5AR80tSFVoYouTrEg_swR73ba2FVEB5UH7MXLQ@mail.gmail.com>
2020-08-31 16:59 ` Stephen Rust
2020-08-31 17:02 ` Doug Dumitru
2020-08-31 17:59 ` Jason Gunthorpe [this message]
2020-09-01 5:56 ` Christoph Hellwig
2020-09-01 7:42 ` Sagi Grimberg
2020-09-01 1:00 ` Ming Lei
2020-09-01 1:10 ` Sagi Grimberg
2020-09-01 2:01 ` Ming Lei
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