From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id SAA27803; Wed, 19 Nov 2003 18:52:08 +0100 (MET) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id SAA27797 for ; Wed, 19 Nov 2003 18:52:07 +0100 (MET) Received: from mail3.bluewin.ch (mail3.bluewin.ch [195.186.1.75]) by nez-perce.inria.fr (8.11.1/8.11.1) with ESMTP id hAJHq7127872 for ; Wed, 19 Nov 2003 18:52:07 +0100 (MET) Received: from [10.0.1.2] (195.186.203.15) by mail3.bluewin.ch (Bluewin AG 7.0.020.2) id 3FA9FE37001DB2B8 for caml-list@inria.fr; Wed, 19 Nov 2003 17:52:06 +0000 Mime-Version: 1.0 (Apple Message framework v606) Content-Transfer-Encoding: 7bit Message-Id: <1970C334-1AB9-11D8-ADB3-000393DBC266@epfl.ch> Content-Type: text/plain; charset=US-ASCII; format=flowed To: caml-list@inria.fr From: =?ISO-8859-1?Q?Daniel_B=FCnzli?= Subject: [Caml-list] Accuracy of Gc.stat () Date: Wed, 19 Nov 2003 18:52:10 +0100 X-Mailer: Apple Mail (2.606) X-Loop: caml-list@inria.fr X-Spam: no; 0.00; runtime:01 utime:01 utime:01 profile:98 profile:98 caml:01 bytecode:01 int:01 int:01 float:02 float:02 pro:97 pro:97 native:02 native:02 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk Since my first attempt [1] didn't really get through, I try to reformulate my post. To compare different implementations of a function I would like to profile its execution in time and heap memory usage (at least orders of magnitude). To do so, I use the code given at the end of this email. Basically I do a full major collection, get the gc statistics via the Gc.stat () function, run my function, call again Gc.stat (), and substract the former statistics to the latters. My questions are : 1) What is the accuracy of these results ? E.g. I read in the documentation of the Gc module that the field minor_words is only an approximation in programs compiled to native code. Is it also true for the other fields ? Would the figure minor+major-promoted be accurate ? How much can I trust the figures I get ? 2) When I start profiling should I prefer a Gc.compact to a Gc.full_major ? 3) Is it possible to know at runtime whether we are running native code or interpreted bytecode ? Regarding time profiling, a binding in the Unix module to the getrusage() function would definitvely be nice. Thanks for your answers, Daniel [1] -- profile.ml -- type t = { minor_bytes : float; promoted_bytes : float; major_bytes : float; allocated_bytes : float; minor_collections : float; major_collections : float; user_time : float; system_time : float } (* Bytes per words *) let bpw = float_of_int (Sys.word_size / 8) (* Heap allocation overhead due to profiling *) let heap_overhead = let s = Gc.stat() in ignore(Unix.times()); ignore(Unix.times()); let s' = Gc.stat() in ((s'.Gc.minor_words +. s'.Gc.major_words -. s'.Gc.promoted_words) -. (s.Gc.minor_words +. s.Gc.major_words -. s.Gc.promoted_words)) *. bpw let execution_stats_n n f a = Gc.full_major (); let s = Gc.stat () in let t = Unix.times () in for i = 1 to n do ignore(f a) done; let t' = Unix.times () in let s' = Gc.stat () in let mi, pro, ma = ((s'.Gc.minor_words -. s.Gc.minor_words) *. bpw) -. heap_overhead, (s'.Gc.promoted_words -. s.Gc.promoted_words) *. bpw, (s'.Gc.major_words -. s.Gc.major_words) *. bpw in let n' = float_of_int n in { minor_bytes = mi /. n'; promoted_bytes = pro /. n'; major_bytes = ma /. n'; allocated_bytes = (mi +. ma -. pro) /. n'; minor_collections = (float_of_int (s'.Gc.minor_collections - s.Gc.minor_collections)) /. n'; major_collections = (float_of_int (s'.Gc.major_collections - s.Gc.major_collections)) /. n'; user_time = (t'.Unix.tms_utime -. t.Unix.tms_utime) /. n'; system_time = (t'.Unix.tms_stime -. t.Unix.tms_stime) /. n' } let execution_stats f a = execution_stats_n 1000 f a let execution f a = execution_stats_n 1 f a ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners