| Message ID | 20220130180256.28303-1-tonylu@linux.alibaba.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | net/smc: Improvements for TCP_CORK and sendfile() | expand |
On Mon, 31 Jan 2022 02:02:54 +0800 Tony Lu wrote: > Currently, SMC use default implement for syscall sendfile() [1], which > is wildly used in nginx and big data sences. Usually, applications use > sendfile() with TCP_CORK: > > fstat(20, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 > setsockopt(19, SOL_TCP, TCP_CORK, [1], 4) = 0 > writev(19, [{iov_base="HTTP/1.1 200 OK\r\nServer: nginx/1"..., iov_len=240}], 1) = 240 > sendfile(19, 20, [0] => [4096], 4096) = 4096 > close(20) = 0 > setsockopt(19, SOL_TCP, TCP_CORK, [0], 4) = 0 > > The above is an example of Nginx, when sendfile() on, Nginx first > enables TCP_CORK, write headers, the data will not be sent. Then call > sendfile(), it reads file and write to sndbuf. When TCP_CORK is cleared, > all pending data is sent out. > > The performance of the default implement of sendfile is lower than when > it is off. After investigation, it shows two parts to improve: > - unnecessary lock contention of delayed work > - less data per send than when sendfile off > > Patch #1 tries to reduce lock_sock() contention in smc_tx_work(). > Patch #2 removes timed work for corking, and let applications control > it. See TCP_CORK [2] MSG_MORE [3]. > Patch #3 adds MSG_SENDPAGE_NOTLAST for corking more data when > sendfile(). > > Test environments: > - CPU Intel Xeon Platinum 8 core, mem 32 GiB, nic Mellanox CX4 > - socket sndbuf / rcvbuf: 16384 / 131072 bytes > - server: smc_run nginx > - client: smc_run ./wrk -c 100 -t 2 -d 30 http://192.168.100.1:8080/4k.html > - payload: 4KB local disk file > > Items QPS > sendfile off 272477.10 > sendfile on (orig) 223622.79 > sendfile on (this) 395847.21 > > This benchmark shows +45.28% improvement compared with sendfile off, and > +77.02% compared with original sendfile implement. > > [1] https://man7.org/linux/man-pages/man2/sendfile.2.html > [2] https://linux.die.net/man/7/tcp > [3] https://man7.org/linux/man-pages/man2/send.2.html I believe this is now commit 780bf05f44c2 ("Merge branch 'smc-improvements'") in net-next. Thanks!
Currently, SMC use default implement for syscall sendfile() [1], which is wildly used in nginx and big data sences. Usually, applications use sendfile() with TCP_CORK: fstat(20, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 setsockopt(19, SOL_TCP, TCP_CORK, [1], 4) = 0 writev(19, [{iov_base="HTTP/1.1 200 OK\r\nServer: nginx/1"..., iov_len=240}], 1) = 240 sendfile(19, 20, [0] => [4096], 4096) = 4096 close(20) = 0 setsockopt(19, SOL_TCP, TCP_CORK, [0], 4) = 0 The above is an example of Nginx, when sendfile() on, Nginx first enables TCP_CORK, write headers, the data will not be sent. Then call sendfile(), it reads file and write to sndbuf. When TCP_CORK is cleared, all pending data is sent out. The performance of the default implement of sendfile is lower than when it is off. After investigation, it shows two parts to improve: - unnecessary lock contention of delayed work - less data per send than when sendfile off Patch #1 tries to reduce lock_sock() contention in smc_tx_work(). Patch #2 removes timed work for corking, and let applications control it. See TCP_CORK [2] MSG_MORE [3]. Patch #3 adds MSG_SENDPAGE_NOTLAST for corking more data when sendfile(). Test environments: - CPU Intel Xeon Platinum 8 core, mem 32 GiB, nic Mellanox CX4 - socket sndbuf / rcvbuf: 16384 / 131072 bytes - server: smc_run nginx - client: smc_run ./wrk -c 100 -t 2 -d 30 http://192.168.100.1:8080/4k.html - payload: 4KB local disk file Items QPS sendfile off 272477.10 sendfile on (orig) 223622.79 sendfile on (this) 395847.21 This benchmark shows +45.28% improvement compared with sendfile off, and +77.02% compared with original sendfile implement. [1] https://man7.org/linux/man-pages/man2/sendfile.2.html [2] https://linux.die.net/man/7/tcp [3] https://man7.org/linux/man-pages/man2/send.2.html Tony Lu (3): net/smc: Send directly when TCP_CORK is cleared net/smc: Remove corked dealyed work net/smc: Cork when sendpage with MSG_SENDPAGE_NOTLAST flag net/smc/af_smc.c | 8 ++++--- net/smc/smc_tx.c | 59 ++++++++++++++++++++++++++++++++---------------- net/smc/smc_tx.h | 3 +++ 3 files changed, 47 insertions(+), 23 deletions(-)