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Date: Tue, 20 Feb 2024 11:52:02 +0800
From: Wen Gu <guwen@...ux.alibaba.com>
To: Wenjia Zhang <wenjia@...ux.ibm.com>, wintera@...ux.ibm.com,
hca@...ux.ibm.com, gor@...ux.ibm.com, agordeev@...ux.ibm.com,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, jaka@...ux.ibm.com, Gerd Bayer <gbayer@...ux.ibm.com>
Cc: borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
alibuda@...ux.alibaba.com, tonylu@...ux.alibaba.com,
linux-s390@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 00/15] net/smc: implement loopback-ism used by
SMC-D
On 2024/2/16 22:09, Wenjia Zhang wrote:
>
>
> On 11.01.24 13:00, Wen Gu wrote:
>> This patch set acts as the second part of the new version of [1] (The first
>> part can be referred from [2]), the updated things of this version are listed
>> at the end.
>>
>> # Background
>>
>> SMC-D is now used in IBM z with ISM function to optimize network interconnect
>> for intra-CPC communications. Inspired by this, we try to make SMC-D available
>> on the non-s390 architecture through a software-implemented virtual ISM device,
>> that is the loopback-ism device here, to accelerate inter-process or
>> inter-containers communication within the same OS instance.
>>
>> # Design
>>
>> This patch set includes 3 parts:
>>
>> - Patch #1-#2: some prepare work for loopback-ism.
>> - Patch #3-#9: implement loopback-ism device.
>> - Patch #10-#15: memory copy optimization for loopback scenario.
>>
>> The loopback-ism device is designed as a ISMv2 device and not be limited to
>> a specific net namespace, ends of both inter-process connection (1/1' in diagram
>> below) or inter-container connection (2/2' in diagram below) can find the same
>> available loopback-ism and choose it during the CLC handshake.
>>
>> Container 1 (ns1) Container 2 (ns2)
>> +-----------------------------------------+ +-------------------------+
>> | +-------+ +-------+ +-------+ | | +-------+ |
>> | | App A | | App B | | App C | | | | App D |<-+ |
>> | +-------+ +---^---+ +-------+ | | +-------+ |(2') |
>> | |127.0.0.1 (1')| |192.168.0.11 192.168.0.12| |
>> | (1)| +--------+ | +--------+ |(2) | | +--------+ +--------+ |
>> | `-->| lo |-` | eth0 |<-` | | | lo | | eth0 | |
>> +---------+--|---^-+---+-----|--+---------+ +-+--------+---+-^------+-+
>> | | | |
>> Kernel | | | |
>> +----+-------v---+-----------v----------------------------------+---+----+
>> | | TCP | |
>> | | | |
>> | +--------------------------------------------------------------+ |
>> | |
>> | +--------------+ |
>> | | smc loopback | |
>> +---------------------------+--------------+-----------------------------+
>>
>> loopback-ism device creates DMBs (shared memory) for each connection peer.
>> Since data transfer occurs within the same kernel, the sndbuf of each peer
>> is only a descriptor and point to the same memory region as peer DMB, so that
>> the data copy from sndbuf to peer DMB can be avoided in loopback-ism case.
>>
>> Container 1 (ns1) Container 2 (ns2)
>> +-----------------------------------------+ +-------------------------+
>> | +-------+ | | +-------+ |
>> | | App C |-----+ | | | App D | |
>> | +-------+ | | | +-^-----+ |
>> | | | | | |
>> | (2) | | | (2') | |
>> | | | | | |
>> +---------------|-------------------------+ +----------|--------------+
>> | |
>> Kernel | |
>> +---------------|-----------------------------------------|--------------+
>> | +--------+ +--v-----+ +--------+ +--------+ |
>> | |dmb_desc| |snd_desc| |dmb_desc| |snd_desc| |
>> | +-----|--+ +--|-----+ +-----|--+ +--------+ |
>> | +-----|--+ | +-----|--+ |
>> | | DMB C | +---------------------------------| DMB D | |
>> | +--------+ +--------+ |
>> | |
>> | +--------------+ |
>> | | smc loopback | |
>> +---------------------------+--------------+-----------------------------+
>>
>> # Benchmark Test
>>
>> * Test environments:
>> - VM with Intel Xeon Platinum 8 core 2.50GHz, 16 GiB mem.
>> - SMC sndbuf/DMB size 1MB.
>> - /sys/devices/virtual/smc/loopback-ism/dmb_copy is set to default 0,
>> which means sndbuf and DMB are merged and no data copied between them.
>> - /sys/devices/virtual/smc/loopback-ism/dmb_type is set to default 0,
>> which means DMB is physically contiguous buffer.
>>
>> * Test object:
>> - TCP: run on TCP loopback.
>> - SMC lo: run on SMC loopback device.
>>
>> 1. ipc-benchmark (see [3])
>>
>> - ./<foo> -c 1000000 -s 100
>>
>> TCP SMC-lo
>> Message
>> rate (msg/s) 80636 149515(+85.42%)
>>
>> 2. sockperf
>>
>> - serv: <smc_run> taskset -c <cpu> sockperf sr --tcp
>> - clnt: <smc_run> taskset -c <cpu> sockperf { tp | pp } --tcp --msg-size={ 64000 for tp | 14 for pp } -i 127.0.0.1
>> -t 30
>>
>> TCP SMC-lo
>> Bandwidth(MBps) 4909.36 8197.57(+66.98%)
>> Latency(us) 6.098 3.383(-44.52%)
>>
>> 3. nginx/wrk
>>
>> - serv: <smc_run> nginx
>> - clnt: <smc_run> wrk -t 8 -c 1000 -d 30 http://127.0.0.1:80
>>
>> TCP SMC-lo
>> Requests/s 181685.74 246447.77(+35.65%)
>>
>> 4. redis-benchmark
>>
>> - serv: <smc_run> redis-server
>> - clnt: <smc_run> redis-benchmark -h 127.0.0.1 -q -t set,get -n 400000 -c 200 -d 1024
>>
>> TCP SMC-lo
>> GET(Requests/s) 85855.34 118553.64(+38.09%)
>> SET(Requests/s) 86824.40 125944.58(+45.06%)
>>
>>
>> Change log:
>>
>> v1->RFC:
>> - Patch #9: merge rx_bytes and tx_bytes as xfer_bytes statistics:
>> /sys/devices/virtual/smc/loopback-ism/xfer_bytes
>> - Patch #10: add support_dmb_nocopy operation to check if SMC-D device supports
>> merging sndbuf with peer DMB.
>> - Patch #13 & #14: introduce loopback-ism device control of DMB memory type and
>> control of whether to merge sndbuf and DMB. They can be respectively set by:
>> /sys/devices/virtual/smc/loopback-ism/dmb_type
>> /sys/devices/virtual/smc/loopback-ism/dmb_copy
>> The motivation for these two control is that a performance bottleneck was
>> found when using vzalloced DMB and sndbuf is merged with DMB, and there are
>> many CPUs and CONFIG_HARDENED_USERCOPY is set [4]. The bottleneck is caused
>> by the lock contention in vmap_area_lock [5] which is involved in memcpy_from_msg()
>> or memcpy_to_msg(). Currently, Uladzislau Rezki is working on mitigating the
>> vmap lock contention [6]. It has significant effects, but using virtual memory
>> still has additional overhead compared to using physical memory.
>> So this new version provides controls of dmb_type and dmb_copy to suit
>> different scenarios.
>> - Some minor changes and comments improvements.
>>
>> RFC->old version([1]):
>> Link: https://lore.kernel.org/netdev/1702214654-32069-1-git-send-email-guwen@linux.alibaba.com/
>> - Patch #1: improve the loopback-ism dump, it shows as follows now:
>> # smcd d
>> FID Type PCI-ID PCHID InUse #LGs PNET-ID
>> 0000 0 loopback-ism ffff No 0
>> - Patch #3: introduce the smc_ism_set_v2_capable() helper and set
>> smc_ism_v2_capable when ISMv2 or virtual ISM is registered,
>> regardless of whether there is already a device in smcd device list.
>> - Patch #3: loopback-ism will be added into /sys/devices/virtual/smc/loopback-ism/.
>> - Patch #8: introduce the runtime switch /sys/devices/virtual/smc/loopback-ism/active
>> to activate or deactivate the loopback-ism.
>> - Patch #9: introduce the statistics of loopback-ism by
>> /sys/devices/virtual/smc/loopback-ism/{{tx|rx}_tytes|dmbs_cnt}.
>> - Some minor changes and comments improvements.
>>
>> [1] https://lore.kernel.org/netdev/1695568613-125057-1-git-send-email-guwen@linux.alibaba.com/
>> [2] https://lore.kernel.org/netdev/20231219142616.80697-1-guwen@linux.alibaba.com/
>> [3] https://github.com/goldsborough/ipc-bench
>> [4] https://lore.kernel.org/all/3189e342-c38f-6076-b730-19a6efd732a5@linux.alibaba.com/
>> [5] https://lore.kernel.org/all/238e63cd-e0e8-4fbf-852f-bc4d5bc35d5a@linux.alibaba.com/
>> [6] https://lore.kernel.org/all/20240102184633.748113-1-urezki@gmail.com/
>>
>> Wen Gu (15):
>> net/smc: improve SMC-D device dump for virtual ISM
>> net/smc: decouple specialized struct from SMC-D DMB registration
>> net/smc: introduce virtual ISM device loopback-ism
>> net/smc: implement ID-related operations of loopback-ism
>> net/smc: implement some unsupported operations of loopback-ism
>> net/smc: implement DMB-related operations of loopback-ism
>> net/smc: register loopback-ism into SMC-D device list
>> net/smc: introduce loopback-ism runtime switch
>> net/smc: introduce loopback-ism statistics attributes
>> net/smc: add operations to merge sndbuf with peer DMB
>> net/smc: attach or detach ghost sndbuf to peer DMB
>> net/smc: adapt cursor update when sndbuf and peer DMB are merged
>> net/smc: introduce loopback-ism DMB type control
>> net/smc: introduce loopback-ism DMB data copy control
>> net/smc: implement DMB-merged operations of loopback-ism
>>
>> drivers/s390/net/ism_drv.c | 2 +-
>> include/net/smc.h | 7 +-
>> net/smc/Kconfig | 13 +
>> net/smc/Makefile | 2 +-
>> net/smc/af_smc.c | 28 +-
>> net/smc/smc_cdc.c | 58 ++-
>> net/smc/smc_cdc.h | 1 +
>> net/smc/smc_core.c | 61 +++-
>> net/smc/smc_core.h | 1 +
>> net/smc/smc_ism.c | 71 +++-
>> net/smc/smc_ism.h | 5 +
>> net/smc/smc_loopback.c | 718 +++++++++++++++++++++++++++++++++++++
>> net/smc/smc_loopback.h | 88 +++++
>> 13 files changed, 1026 insertions(+), 29 deletions(-)
>> create mode 100644 net/smc/smc_loopback.c
>> create mode 100644 net/smc/smc_loopback.h
>>
> Hi Wen,
>
> Thank you for the patience again!
>
> You can find the comments under the corresponding patches respectively.
> About the file hierarchy in sysfs and the names, we still have some thoughts. We need to investigate a bit more time on it.
>
Hi Wenjia and Gerd,
Thank you very much!
I answered each comment you left. You can find my thoughts about sysfs and
knobs there. Looking forward to your further reply. Thanks!
Best regards,
Wen Gu
> Thanks,
> Gerd & Wenjia
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