<div class="gmail_quote">On Fri, Jan 16, 2009 at 12:44 PM, YC <<a href="mailto:yinso.chen@gmail.com">yinso.chen@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> <div class="gmail_quote"><div>Thanks for verifying, Matthew.  I did a quick test and found that the overhead is minimal.  I also compared against `substring` as reference, and found that regular string port still has a bit of overhead above substring.  Is the overhead due to synchronization primitives? Thanks, yc </div></div></blockquote><div> I just realized that I double counted on `test-port` as I did two separate operation - `read-bytes` & `file-position`.  By changing it to `peek-bytes` the test is now fairer to the ports.  A slight overhead of bytes port still exists over substring though.  And the wrapped port's overhead is smaller as well. Thanks, yc (define (test-port in count)   (for ((i (in-range 0 count)))        (peek-bytes 50 0 in ))) (test 500) ;; cpu time: 1 real time: 0 gc time: 0 ;; cpu time: 0 real time: 1 gc time: 0 ;; cpu time: 0 real time: 0 gc time: 0 (test 5000) ;; cpu time: 3 real time: 3 gc time: 0 ;; cpu time: 34 real time: 35 gc time: 31 ;; cpu time: 2 real time: 2 gc time: 0 (test 50000) ;; cpu time: 24 real time: 24 gc time: 0 ;; cpu time: 27 real time: 27 gc time: 1 ;; cpu time: 19 real time: 20 gc time: 2 (test 500000) ;; cpu time: 163 real time: 163 gc time: 3 ;; cpu time: 173 real time: 173 gc time: 2 ;; cpu time: 135 real time: 135 gc time: 9 (test 5000000) ;; cpu time: 1594 real time: 1598 gc time: 63 ;; cpu time: 1761 real time: 1760 gc time: 61 ;; cpu time: 1456 real time: 1456 gc time: 208 </div></div>