context negotiation performance problem

[Eric Mei]

Hi,

I searched archive but didn't find the answer.

I made a simple test for security context negotiation of MIT krb5-1.3.5, 
under Linux, driven by GSSAPI: client call gss_init_sec_context() and 
send token to server, server call gss_accept_sec_context() and send back 
the result token.

on a P4 1.6G machine, the server only could handle ~10 requests per 
second, and there's lots of disk I/O during running. By strace, I found 
krb5 libraries created a temp file under "/var/tmp", and call following 
syscalls for each request:
    write(fd, data, 50);
    fsync(fd);
The fsync() certainly lead to low performance. Anybody know why it is here?

Besides the fsync(), vmstat shows ~200 blocks write per seconds. It 
seems the above "write(fd, data, 50)" can't produce that much data. So 
where those write come from? Are there any other known issue might 
affect performance?

Our server might experience 1000s of context negotiation requests at the 
same time, so the above performance problem looks serious to us.

Thanks a lot for any help!

Eric