On Fri, Mar 22, 2002 at 01:34:48AM -0800, Guy Harris wrote: > On Thu, Mar 21, 2002 at 03:40:38PM -0800, Guy Harris wrote: > > If I remember correctly, there might be, in at least some versions of > > the kernel, some configuration flag you have to turn on to get time > > stamps of various sorts to use high-resolution timers. Does anybody > > know what they are? That would be useful to put into the tcpdump FAQ. > > It looks as if, on x86 boxes, the CONFIG_X86_TSC has to be enabled, in > at least some kernels, in order to get high-resolution time stamps.
Yes. I verified that it was enabled on the RH7.2 systems. I even added a #error directive to time.c in the slow_gettimeoffset() routine before compiling. That should prevent the kernel from even building without CONFIG_X86_TSC enabled. I also verfied that calling gettimeofday() from a usertask has 1us resolution even though the timestamps privded to libpcap have 10ms resolution. If CONFIG_X86_TSC was not enabled, it's my understanding that the gettimeofday() libc call would only have a resolution of 10ms. -- Grant Edwards [EMAIL PROTECTED] - This is the TCPDUMP workers list. It is archived at http://www.tcpdump.org/lists/workers/index.html To unsubscribe use mailto:[EMAIL PROTECTED]?body=unsubscribe
