DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5102420851
Date:   Tue, 11 Dec 2018 23:18:42 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        linux-rdma@vger.kernel.org,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v3 05/24] xprtrdma: Reduce max_frwr_depth
Message-ID: <20181212071842.GB23247@infradead.org>
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 <20181211140242.GC30471@infradead.org>
 <69E69F06-4B3C-4C91-9412-3E7FE14C2ADA@oracle.com>
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On Tue, Dec 11, 2018 at 10:30:24AM -0500, Chuck Lever wrote:
> 
> 
> > On Dec 11, 2018, at 9:02 AM, Christoph Hellwig <hch@infradead.org> wrote:
> > 
> > On Mon, Dec 10, 2018 at 11:29:45AM -0500, Chuck Lever wrote:
> >> Some devices advertise a large max_fast_reg_page_list_len
> >> capability, but perform optimally when MRs are significantly smaller
> >> than that depth -- probably when the MR itself is no larger than a
> >> page.
> >> 
> >> By default, the RDMA R/W core API uses max_sge_rd as the maximum
> >> page depth for MRs. For some devices, the value of max_sge_rd is
> >> 1, which is also not optimal. Thus, when max_sge_rd is larger than
> >> 1, use that value. Otherwise use the value of the
> >> max_fast_reg_page_list_len attribute.
> >> 
> >> I've tested this with a couple of devices, and it reproducibly
> >> improves the throughput of large I/Os by several percent.
> > 
> > Can you list which devices for reference in the changelog?
> 
> I have only three devices here. I can't make an exhaustive list.

Just list the onces you've tested.