Performance with X

I usually feel interactivity stress when running background buildworld
on X.  This benchmark is not strict, but I can see the trend.

My box is dual Pentium-III 800MHz with 2GB memory and Matrox G450 AGP
card.  Kernel is compiled with SCHED_4BSD now, but there is only small
difference with _ULE.

With X, this shows too many context switches, and takes doubled time.
When I check systat -vm, "Interrupts" of drm is 40% of total even if
in idle.

Is there anything I can improve the performance of this box?


----- time(1) output of make -j2 without X
     1561.49 real      1213.73 user       855.41 sys
     60676  maximum resident set size
      2142  average shared memory size
      1134  average unshared data size
       125  average unshared stack size
   5706397  page reclaims
       152  page faults
         0  swaps
      1181  block input operations
      1451  block output operations
         0  messages sent
         0  messages received
      7472  signals received
   1170457  voluntary context switches
    305224  involuntary context switches


----- time(1) output of make -j2 with X
     3882.32 real      1206.42 user      2985.05 sys
     60676  maximum resident set size
      1647  average shared memory size
       863  average unshared data size
       125  average unshared stack size
   5705483  page reclaims
         0  page faults
         0  swaps
       424  block input operations
      1355  block output operations
         0  messages sent
         0  messages received
      7506  signals received
   1834731  voluntary context switches
    708232  involuntary context switches


----- typical "Interrupts" output from systat -vm with X in idle
nterrupts
398 total
    1: atkb
    4: sio0
    5: uhci
    6: fdc0
128 8: rtc
    12: psm
    13: npx
    14: ata
    15: ata
170 16: drm
    18: ata
    19: fwo
100 0: clk


-- 
Jun Kuriyama <kuriyama_at_imgsrc.co.jp> // IMG SRC, Inc.
             <kuriyama_at_FreeBSD.org> // FreeBSD Project