That was very nearly the right answer#

Mon Sep 1 21:22:14 2003

Topics:

That was very nearly the right answer. In fact

there are a couple of places that write-protect pages, so both need to check the dont_move bit
GC wipes out dont_move on all pages at the start of GC, before running preserve_pointers(). preserve_pointers only looks at the 'from' space (after all, we're not moving objects anyway unless they're in in fromspace), so when we see these pages again later we no longer have them specially marked, so we write-protect them as normal. Wrong. Having realised the problem, the solution is simple: only reset dont_move on fromspace pages instead of on all pages.

:; /usr/sbin/ab -c5 -n10000 http://xxxxxxxxxxxxxxxxxxx:8009/Welcome
[...]
Server Software:        Araneida/0.74                                      
Server Hostname:        xxxxxxxxxxxxxxxxxxx
Server Port:            8009

Document Path:          /Welcome
Document Length:        2796 bytes

Concurrency Level:      5
Time taken for tests:   190.112 seconds
Complete requests:      10000
Failed requests:        0
Broken pipe errors:     0
Total transferred:      29582958 bytes
HTML transferred:       27962796 bytes
Requests per second:    52.60 [#/sec] (mean)
Time per request:       95.06 [ms] (mean)
Time per request:       19.01 [ms] (mean, across all concurrent requests)
Transfer rate:          155.61 [Kbytes/sec] received

Connnection Times (ms)
              min  mean[+/-sd] median   max
Connect:      -10     0   12.0      0   848
Processing:     7    42  104.7     17  1998
Waiting:        0    41  104.1     16  1998
Total:          7    42  105.9     17  1998

Percentage of the requests served within a certain time (ms)
  50%     17
  66%     25
  75%     34
  80%     42
  90%     66
  95%    105
  98%    285
  99%    665
 100%   1998 (last request)

10000 requests later with no problems, and i think we've got this nailed.