These are some notes on how HTTP/1.1 affects the system overhead in Web applications compared to HTTP/1.0. The measurements were taking using truss on Solaris 2.5 with Java 1.1.1. The results are listed below. The test was run gainst the microscape site which is expmained in the paper "Network Performance Effects of HTTP/1.1, CSS1, and PNG" (1 HTML and 43 GIFS)
Note that the number of stat calls is higher when using Netscape than using the Libwww robot as Netscape tends to download repeated images multiple times. The elapsed time was how long truss was running and not how long the download took. The amount of read calls and context calls differs significantly between the robot and Netscape's browsers - especially the Communicator seems to be bad at this.
What is interesting is that the number of write calls also is significantly lower. The reason for this is that the persistent connection allows Jigsaw to buffer its output better than when using multiple connections.
I assume that the errors column in the tables below is when a system call returns something different from 0.
No offence against NS's browsers - I could have picked any other HTTP/1.0 browser!
syscall seconds calls errors read .00 104 1 write .02 45 8 open .00 44 close .00 44 stat .00 43 pause .00 20 20 access .02 43 ioctl .02 183 129 fcntl .00 92 getmsg .00 14 12 poll .00 12 sigprocmask .01 184 context .03 617 setitimer .00 55 ---- --- --- sys totals: .10 1500 170 usr time: .62 elapsed: 11.37
syscall seconds calls errors read .00 333 187 write .02 63 3 open .01 49 close .00 45 stat .00 45 pause .00 62 62 access .01 45 ioctl .02 224 135 fcntl .00 114 getmsg .00 61 53 poll .00 54 sigprocmask .00 218 context .10 1115 setitimer .00 78 ---- --- --- sys totals: .16 2506 440 usr time: .82 elapsed: 13.13
syscall seconds calls errors read .03 465 325 write .01 67 6 open .00 45 close .00 43 stat .00 43 pause .00 23 23 access .00 43 ioctl .00 194 129 fcntl .00 98 getmsg .00 53 49 poll .00 50 sigprocmask .02 204 context .20 3598 setitimer .00 51 ---- --- --- sys totals: .26 4977 532 usr time: .75 elapsed: 5.04