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Message-ID: <a95ed8a0-0f31-431c-aa4c-d81e2efcbf6d@linux.ibm.com>
Date: Fri, 8 Mar 2024 13:22:31 +0100
From: Jan Karcher <jaka@...ux.ibm.com>
To: Wen Gu <guwen@...ux.alibaba.com>, wintera@...ux.ibm.com,
twinkler@...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, wenjia@...ux.ibm.com
Cc: borntraeger@...ux.ibm.com, svens@...ux.ibm.com, alibuda@...ux.alibaba.com,
tonylu@...ux.alibaba.com, linux-kernel@...r.kernel.org,
linux-s390@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 00/11] net/smc: SMC intra-OS shortcut with
loopback-ism
On 07/03/2024 10:55, 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.
Hi Wen Gu,
thanks for the updated patch. Please givr me some time to review and
test the latest version.
Thanks
- Jan
>
> - 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 Emulated-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-#7: implement loopback-ism device. Noted that loopback-ism now
> serves only SMC and no userspace interface exposed.
> - Patch #10-#15: memory copy optimization for intra-OS scenario.
>
> The loopback-ism device is designed as an 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.
>
> * Test object:
> - TCP: run on TCP loopback.
> - SMC lo: run on SMC loopback-ism.
>
> 1. ipc-benchmark (see [3])
>
> - ./<foo> -c 1000000 -s 100
>
> TCP SMC-lo
> Message
> rate (msg/s) 79287 148946(+87.86%)
>
> 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) 5053.47 8195.07(+62.17%)
> Latency(us) 6.108 3.404(-44.27%)
>
> 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 178187.56 247970.92(+39.16%)
>
> 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) 89067.02 123877.36(+39.08%)
> SET(Requests/s) 87700.07 131319.77(+49.73%)
>
>
> Change log:
>
> v2->v1:
> - All the patches: changed the term virtual-ISM to Emulated-ISM as defined by SMCv2.1.
> - Patch #3: optimized the description of SMC_LO config. Avoid exposing loopback-ism
> to sysfs and remove all the knobs until future definition clear.
> - Patch #3: try to make lockdep happy by using read_lock_bh() in smc_lo_move_data().
> - Patch #6: defaultly use physical contiguous DMB buffers.
> - Patch #11: defaultly enable DMB no-copy for loopback-ism and free the DMB in
> unregister_dmb or detach_dmb when dmb_node->refcnt reaches 0, instead of using
> wait_event to keep waiting in unregister_dmb.
>
> 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 (11):
> net/smc: adapt SMC-D device dump for Emulated-ISM
> net/smc: decouple ism_client from SMC-D DMB registration
> net/smc: introduce loopback-ism for SMC intra-OS shortcut
> 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: 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: 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 | 469 +++++++++++++++++++++++++++++++++++++
> net/smc/smc_loopback.h | 52 ++++
> 13 files changed, 741 insertions(+), 29 deletions(-)
> create mode 100644 net/smc/smc_loopback.c
> create mode 100644 net/smc/smc_loopback.h
>
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