On 5/18/2018 1:58 PM, Long Li wrote:
Subject: Re: [RFC PATCH 09/09] Introduce cache=rdma moutning option
On Fri, May 18, 2018 at 12:00 PM, Long Li via samba-technical <samba-
technical@xxxxxxxxxxxxxxx> wrote:
Subject: Re: [RFC PATCH 09/09] Introduce cache=rdma moutning option
On Thu, May 17, 2018 at 05:22:14PM -0700, Long Li wrote:
From: Long Li <longli@xxxxxxxxxxxxx>
When cache=rdma is enabled on mount options, CIFS do not allocate
internal data buffer pages for I/O, data is read/writen directly to
user
memory via RDMA.
I don't think this should be an option. For direct I/O without
signing or encryption CIFS should always use get_user_pages, with or
without RDMA.
Yes this should be done for all transport. If there are no objections, I'll send
patches to change this.
Would this help/change performance much?
On RDMA, it helps with I/O latency and reduces CPU usage on certain I/O patterns.
But I haven't tested on TCP. Maybe it will help a little bit.
Well, when the application requests direct i/o on a TCP connection,
you definitely don't want to cache it! So even if the performance
is different, correctness would dictate doing this.
You probably don't need to pin the buffer in the TCP case, which
might be worth avoiding.
Tom.
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
