Hello ! Many thanks all for your answers !
Managing to have the almost same performance whether in mutithreaded environment or not (even not using threads for this particular task) is something I would like to have anyway. I'll give a try to big buffers using Using.read. Any example code around ? And then why not try iao ! Memory mapping of the file could be done using BigArray or do I have to write C code ? Rémi On Tue, Feb 17, 2009 at 11:26, Mark Shinwell <mshinw...@janestcapital.com>wrote: > On Tue, Feb 17, 2009 at 10:07:05AM +0000, Sylvain Le Gall wrote: > > On 17-02-2009, Rémi Dewitte <r...@gide.net> wrote: > > You are using input_char and standard IO channel. This is a good choice > > for non-threaded program. But in your case, I will use Unix.read with a > > big buffer (32KB to 4MB) and change your program to use it. As > > benchmarked by John Harrop, you are spending most of your time in > > caml_enter|leave_blocking section. > > This isn't quite right actually -- the profile is deceiving. It is true > that there are a lot of calls to enter/leave_blocking_section, but you're > actually being killed by the overhead of an independent locking strategy > in the channel-based I/O calls. I've measured this using some hackery > with a hex editor. When you call input_char, you acquire and then release > another lock which is specific to these calls (the global runtime lock is > often not released here). This process isn't especially cheap, so it would > be better to use one of the other channel calls to read data in larger > blocks. > > Mark >
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