FC4 kernel performance

[Dave Jones]

On Tue, Jun 21, 2005 at 02:17:59PM -0400, Malita, Florin wrote:
 > On Tue, 2005-06-21 at 11:47 -0400, Dave Jones wrote:
 > > Which is an apples to oranges comparison. 2.6.11-1.1369_FC4 is 
 > > actually based on 2.6.12rc6.  I'll be interested in seeing results 
 > > rerun against this kernel.
 > 
 > Back with some apples: http://lufs.sourceforge.net/unixbench.html
 > 
 > Now I have:
 > 
 > 1. Linux 2.6.12-rc6 (nodebug+p4+nose+nohm+lean): 355.7
 > 2. Linux 2.6.11.12 (nodebug+p4+nose+nohm+lean): 345.8 
 > 3. Linux 2.6.11-1.1369_FC4 (nodebug+p4+nose+nohm+lean): 269.3 
 > 4. Linux 2.6.11-1.1369_FC4 (nodebug+p4+nose+ nohm): 253.1 
 > 5. Linux 2.6.11-1.1369_FC4 (nodebug+p4): 239.4 
 > 6. Linux 2.6.11-1.1369_FC4 (nodebug): 236.7 
 > 7: Linux 2.6.11-1.1369_FC4 (orig): 213.2 
 > 8: SunOS 5.11 (orig): 122.3 
 > 
 > (1, 2 & 3 here share the same configuration)
 > 
 > So 2.6.12-rc6 is slightly better overall than 2.6.11.12 and still a lot
 > faster than FC4 (especially in the syscall overhead & pipe throughput
 > area).

Thanks, I'll take a look at this later.

 > Am I correct in assuming the FC kernel doesn't use the vsyscall/sysenter
 > mechanism thus taking a serious performance hit on P4s?

Correct. (Unless you have a CPU with NX).
I think we'd also be able to reenable sysenter if we booted with exec_sheild=0,
but currently we don't handle that case (we just always disable if no NX present)

		Dave