On Mon, Apr 16, 2018 at 11:43 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > > > On 04/16/2018 08:33 AM, Yafang Shao wrote: >> tcp_rcv_space_adjust is called every time data is copied to user space, >> introducing a tcp tracepoint for which could show us when the packet is >> copied to user. >> This could help us figure out whether there's latency in user process. >> >> When a tcp packet arrives, tcp_rcv_established() will be called and with >> the existed tracepoint tcp_probe we could get the time when this packet >> arrives. >> Then this packet will be copied to user, and tcp_rcv_space_adjust will >> be called and with this new introduced tracepoint we could get the time >> when this packet is copied to user. >> >> arrives time : user process time => latency caused by user >> tcp_probe tcp_rcv_space_adjust >> >> Hence in the prink message, sk is printed as a key to connect these two >> tracepoints. >> > > socket pointer is not a key. > > TCP sockets can be reused pretty fast after free. > > I suggest you go for cookie instead, this is an unique 64bit identifier. > ( sock_gen_cookie() for details ) > >
Thanks for your explanation. Will have a try. Thanks Yafang
