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@xxxxxxxxxxxxxxxxx/ - 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@xxxxxxxxxxxxxxxxx/ [2] https://lore.kernel.org/netdev/20231219142616.80697-1-guwen@xxxxxxxxxxxxxxxxx/ [3] https://github.com/goldsborough/ipc-bench [4] https://lore.kernel.org/all/3189e342-c38f-6076-b730-19a6efd732a5@xxxxxxxxxxxxxxxxx/ [5] https://lore.kernel.org/all/238e63cd-e0e8-4fbf-852f-bc4d5bc35d5a@xxxxxxxxxxxxxxxxx/ [6] https://lore.kernel.org/all/20240102184633.748113-1-urezki@xxxxxxxxx/ 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 -- 2.32.0.3.g01195cf9f