On Mon, Apr 25, 2016 at 5:44 PM, Martin KaFai Lau <ka...@fb.com> wrote: > v4: > ~ Do not set eor bit in do_tcp_sendpages() since there is > no way to pass MSG_EOR from the userland now. > ~ Avoid rmw by testing MSG_EOR first in tcp_sendmsg(). > ~ Move TCP_SKB_CB(skb)->eor test to a new helper > tcp_skb_can_collapse_to() (suggested by Soheil). > ~ Add some packetdrill tests.
Thanks for the nice patches and the tests! > v3: > ~ Separate EOR marking from the SKBTX_ANY_TSTAMP logic. > ~ Move the eor bit test back to the loop in tcp_sendmsg and > tcp_sendpage because there could be >1 threads doing > sendmsg. > ~ Thanks to Eric Dumazet's suggestions on v2. > ~ The TCP timestamp bug fixes are separated into other threads. > > v2: > ~ Rework based on the recent work > "add TX timestamping via cmsg" by > Soheil Hassas Yeganeh <soheil.k...@gmail.com> > ~ This version takes the MSG_EOR bit as a signal of > end-of-response-message and leave the selective > timestamping job to the cmsg > ~ Changes based on the v1 feedback (like avoid > unlikely check in a loop and adding tcp_sendpage > support) > ~ The first 3 patches are bug fixes. The fixes in this > series depend on the newly introduced txstamp_ack in > net-next. I will make relevant patches against net after > getting some feedback. > ~ The test results are based on the recently posted net fix: > "tcp: Fix SOF_TIMESTAMPING_TX_ACK when handling dup acks" > > One potential use case is to use MSG_EOR with > SOF_TIMESTAMPING_TX_ACK to get a more accurate > TCP ack timestamping on application protocol with > multiple outgoing response messages (e.g. HTTP2). > > One of our use case is at the webserver. The webserver tracks > the HTTP2 response latency by measuring when the webserver sends > the first byte to the socket till the TCP ACK of the last byte > is received. In the cases where we don't have client side > measurement, measuring from the server side is the only option. > In the cases we have the client side measurement, the server side > data can also be used to justify/cross-check-with the client > side data. >
