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Date: Fri, 12 Jan 2024 20:32:14 +0800
From: Wen Gu <guwen@...ux.alibaba.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: wintera@...ux.ibm.com, wenjia@...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,
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 2024/1/12 17:10, Jiri Pirko wrote:
> Fri, Jan 12, 2024 at 09:29:35AM CET, guwen@...ux.alibaba.com wrote:
>>
>>
<...>
>>>> 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,
>>>
>>> Exposing any configuration knobs and statistics over sysfs for
>>> softdevices does not look correct at all :/ Could you please avoid
>>> sysfs?
>>>
>>
>> In previous reviews and calls, we think loopback-ism needs to be more
>> like a device and be visible under /sys/devices.
>>
>> Would you mind explaining why using sysfs for loopback-ism is not correct?
>> since I saw some other configurations or statistics exists under /sys/devices,
>> e.g. /sys/devices/virtual/net/lo. Thank you!
>
> You have smc_netlink.c exposing clear netlink api for the subsystem.
> Can't you extend it to contain the configuration knobs and expose stats
> instead of sysfs?
>
Thank you for the suggestion. I've also considered this approach.
But I didn't choose to extend the smc netlink because for now smc netlink
are used for SMC protocol related attributes, for example:
SMC_NETLINK_GET_SYS_INFO: SMC version, release, v2-capable..
SMC_NETLINK_GET_LGR_SMC{R|D}: SMC-{R|D} link group inform (lgr id, lgr conn num, lgr role..)
SMC_NETLINK_GET_LINK_SMCR: SMC-R link inform (link id, link state, conn cnt..)
SMC_NETLINK_GET_DEV_SMCD: SMC-D device generic inform (user cnt, pci_fid, pci_chid, pci_vendor..)
SMC_NETLINK_GET_DEV_SMCR: SMC-R device generic inform (dev name, port pnet_id, port valid, port state..)
SMC_NETLINK_GET_STATS: SMC generic stats (RMB cnt, Tx size, Rx size, RMB size...)
And the knobs and stats in this patchset are loopback-ism device specific
attributes, for example:
active: loopback-ism runtime switch
dmb_type: type of DMB provided by loopback-ism
dmb_copy: support for DMB merge of loopback-ism
xfer_bytes: data transferred by loopback-ism
dmbs_cnt: DMB num provided by loopback-ism
The layer will be:
+--------------------------------------+
| |
| SMC protocol |
| (attrs by netlink in smc_netlink.c) |
| |
+--------------------------------------+
------------------smcd_ops------------------
+---------------+ +---------------------+ +--------------+
| loopback-ism | | s390 firmware ISM | | Possible |
+---------------+ | | | other |
(attrs by sysfs | | | virtual ISM |
in smc_loopback.c) | | | |
| | | |
+---------------------+ +--------------+
So I choose to use current way to provide this lower layer loopback-ism
device's attributes, restrict loopback-ism specific code to smc_loopback.c
and try to make a clear layer architecture.
Thanks,
Wen Gu
>
>>
>>
>>
>> Thanks again,
>> Wen Gu
>>
>>>
>>>> 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
>>>>
>>>> --
>>>> 2.32.0.3.g01195cf9f
>>>>
>>>>
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