From: Wen Gu <guwen@linux.alibaba.com>
To: Niklas Schnelle <schnelle@linux.ibm.com>,
wintera@linux.ibm.com, wenjia@linux.ibm.com, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
jaka@linux.ibm.com
Cc: borntraeger@linux.ibm.com, svens@linux.ibm.com,
alibuda@linux.alibaba.com, tonylu@linux.alibaba.com,
linux-s390@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 14/15] net/smc: introduce loopback-ism DMB data copy control
Date: Sat, 13 Jan 2024 15:12:00 +0800 [thread overview]
Message-ID: <c828acfe-412a-4555-85a9-573e78833ec9@linux.alibaba.com> (raw)
In-Reply-To: <e0b80a1680ccc693de3f29bfaa9fa654c3b7b4fa.camel@linux.ibm.com>
On 2024/1/13 00:24, Niklas Schnelle wrote:
> On Thu, 2024-01-11 at 20:00 +0800, Wen Gu wrote:
>> This provides a way to {get|set} whether loopback-ism device supports
>> merging sndbuf with peer DMB to eliminate data copies between them.
>>
>> echo 0 > /sys/devices/virtual/smc/loopback-ism/dmb_copy # support
>> echo 1 > /sys/devices/virtual/smc/loopback-ism/dmb_copy # not support
>
> The two support/no support remarks are a bit confusing because support
> here seems to mean "support no-copy mode" while the attribute is more
> like "force copy mode". How about:
>
> echo 0 > /sys/devices/virtual/smc/loopback-ism/dmb_copy # one DMB mode
> echo 1 > /sys/devices/virtual/smc/loopback-ism/dmb_copy # copy mode
>
Thank you! Niklas.
That makes it much clearer. It will be improved in next version.
>>
>> The settings take effect after re-activating loopback-ism by:
>>
>> echo 0 > /sys/devices/virtual/smc/loopback-ism/active
>> echo 1 > /sys/devices/virtual/smc/loopback-ism/active
>>
>> After this, the link group related to loopback-ism will be flushed and
>> the sndbufs of subsequent connections will be merged or not merged with
>> peer DMB.
>>
>> The motivation of this control is that the bandwidth will be highly
>> improved when sndbuf and DMB are merged, but when virtually contiguous
>> DMB is provided and merged with sndbuf, it will be concurrently accessed
>> on Tx and Rx, then there will be a bottleneck caused by lock contention
>> of find_vmap_area when there are many CPUs and CONFIG_HARDENED_USERCOPY
>> is set (see link below). So an option is provided.
>>
>> Link: https://lore.kernel.org/all/238e63cd-e0e8-4fbf-852f-bc4d5bc35d5a@linux.alibaba.com/
>> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> ---8<---
next prev parent reply other threads:[~2024-01-13 7:12 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-11 12:00 [PATCH net-next 00/15] net/smc: implement loopback-ism used by SMC-D Wen Gu
2024-01-11 12:00 ` [PATCH net-next 01/15] net/smc: improve SMC-D device dump for virtual ISM Wen Gu
2024-01-11 12:00 ` [PATCH net-next 02/15] net/smc: decouple specialized struct from SMC-D DMB registration Wen Gu
2024-01-11 12:00 ` [PATCH net-next 03/15] net/smc: introduce virtual ISM device loopback-ism Wen Gu
2024-02-16 14:11 ` Wenjia Zhang
2024-02-20 1:20 ` Wen Gu
2024-01-11 12:00 ` [PATCH net-next 04/15] net/smc: implement ID-related operations of loopback-ism Wen Gu
2024-01-11 12:00 ` [PATCH net-next 05/15] net/smc: implement some unsupported " Wen Gu
2024-01-11 12:00 ` [PATCH net-next 06/15] net/smc: implement DMB-related " Wen Gu
2024-02-16 14:13 ` Wenjia Zhang
2024-02-20 1:55 ` Wen Gu
2024-02-23 14:12 ` Wenjia Zhang
2024-02-26 3:04 ` Wen Gu
2024-01-11 12:00 ` [PATCH net-next 07/15] net/smc: register loopback-ism into SMC-D device list Wen Gu
2024-01-11 12:00 ` [PATCH net-next 08/15] net/smc: introduce loopback-ism runtime switch Wen Gu
2024-01-11 12:00 ` [PATCH net-next 09/15] net/smc: introduce loopback-ism statistics attributes Wen Gu
2024-02-16 14:24 ` Wenjia Zhang
2024-02-20 2:45 ` Wen Gu
2024-02-23 14:13 ` Wenjia Zhang
2024-02-26 12:58 ` Wen Gu
2024-01-11 12:00 ` [PATCH net-next 10/15] net/smc: add operations to merge sndbuf with peer DMB Wen Gu
2024-01-11 12:00 ` [PATCH net-next 11/15] net/smc: attach or detach ghost sndbuf to " Wen Gu
2024-01-11 12:00 ` [PATCH net-next 12/15] net/smc: adapt cursor update when sndbuf and peer DMB are merged Wen Gu
2024-01-11 12:00 ` [PATCH net-next 13/15] net/smc: introduce loopback-ism DMB type control Wen Gu
2024-02-16 14:25 ` Wenjia Zhang
2024-02-20 3:19 ` Wen Gu
2024-01-11 12:00 ` [PATCH net-next 14/15] net/smc: introduce loopback-ism DMB data copy control Wen Gu
2024-01-12 16:24 ` Niklas Schnelle
2024-01-13 7:12 ` Wen Gu [this message]
2024-02-16 14:25 ` Wenjia Zhang
2024-02-20 3:36 ` Wen Gu
2024-02-23 14:42 ` Wenjia Zhang
2024-01-11 12:00 ` [PATCH net-next 15/15] net/smc: implement DMB-merged operations of loopback-ism Wen Gu
2024-01-11 13:36 ` [PATCH net-next 00/15] net/smc: implement loopback-ism used by SMC-D Simon Horman
2024-01-12 2:54 ` Wen Gu
2024-01-11 14:50 ` Jiri Pirko
2024-01-12 8:29 ` Wen Gu
2024-01-12 9:10 ` Jiri Pirko
2024-01-12 12:32 ` Wen Gu
2024-01-12 15:50 ` Jiri Pirko
2024-01-13 9:22 ` Wen Gu
2024-01-15 14:11 ` Jiri Pirko
2024-01-18 8:27 ` Wen Gu
2024-01-18 13:59 ` Wenjia Zhang
2024-01-19 1:46 ` Wen Gu
2024-01-23 14:03 ` Alexandra Winter
2024-01-24 6:33 ` Wen Gu
2024-02-05 10:05 ` Wen Gu
2024-02-07 9:08 ` Wenjia Zhang
2024-02-06 12:18 ` Alexandra Winter
2024-02-08 16:12 ` Wen Gu
2024-02-19 14:04 ` Wen Gu
2024-02-16 14:09 ` Wenjia Zhang
2024-02-20 3:52 ` Wen Gu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c828acfe-412a-4555-85a9-573e78833ec9@linux.alibaba.com \
--to=guwen@linux.alibaba.com \
--cc=agordeev@linux.ibm.com \
--cc=alibuda@linux.alibaba.com \
--cc=borntraeger@linux.ibm.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=gor@linux.ibm.com \
--cc=hca@linux.ibm.com \
--cc=jaka@linux.ibm.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=schnelle@linux.ibm.com \
--cc=svens@linux.ibm.com \
--cc=tonylu@linux.alibaba.com \
--cc=wenjia@linux.ibm.com \
--cc=wintera@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).