On Tuesday 04 July 2006 13:41, Jesper Dangaard Brouer wrote: > > On Mon, 26 Jun 2006, Andi Kleen wrote: > > >> I encountered the same problem on a dual core opteron equipped with a > >> broadcom NIC (tg3) under 2.4. It could receive 1 Mpps when using TSC > >> as the clock source, but the time jumped back and forth, so I changed > >> it to 'notsc', then the performance dropped dramatically to around the > >> same value as above with one CPU saturated. I suspect that the clock > >> precision is needed by the tg3 driver to correctly decide to switch to > >> polling mode, but unfortunately, the performance drop rendered the > >> solution so much unusable that I finally decided to use it only in > >> uniprocessor with TSC enabled. > > > > 2.6 is more clever at this than 2.4. In particular it does the timestamp > > for each packet only when actually needed, which is relativelt rare. > > > > Old experiences do not always apply to new kernels. > > Note, that I experinced this problem on 2.6. > > Actually the change happens between kernel version 2.6.15 and 2.6.16.
The timestamp optimizations are older. Don't remember the exact release, but earlier 2.6. > And > is a result of Andi's changes to arch/x86_64/Kconfig and > drivers/acpi/Kconfig, which "allows/activates" the use of the timer on > x86_64. Not sure what you mean here? 2.6.18 will likely be more aggressive at using the TSC on i386 on Intel systems where possible, but x86-64 did this already for a long time. When x86-64 uses non TSC then it's because using the TSC is not safe. -Andi - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
