I've written a command-line tool in Racket to analyze the files produced by a
tool that traces accesses to persistent memory by an application. The traces
are large: about 5 million records per second of application run time. While
developing the tool in Racket was a pleasant, productive, and educational
experience, the execution time of the tool has become an issue. I have some
ideas of ways to improve the analysis logic, but I think the trace reader may
perform so slowly that the result would still be unusable.
The trace records are in a binary format. I have a C++ tool that reads the
binary trace file and outputs them in a simple sxml-ish textual form to stdout.
I pipe this into my Racket tool, that then uses the standard Racket reader to
parse the s-expressions arriving on its stdin. I excised all the analysis code
from from my tool and just benchmarked the performance of the trace reader. It
can only read about 62,000 s-expressions per second on a 2.4 GHz Xeon E5-2630
v3 (Haswell) system. I'm using Racket v6.7.
I've provided the trace reader code below. Have I botched something that would
make it perform so slowly? I'd rather not have to recode it in C++.
The input to the tool looks like this:
(pmem_flush
(threadId 140339047277632)
(startTime 923983542377819)
(elapsedTime 160)
(result 0)
(addr 0x7fa239055954)
(length 1))
(pmem_drain
(threadId 140339047277632)
(startTime 923983542378153)
(elapsedTime 83)
(result 0))
The trace record reader code:
#! /usr/bin/env racket
#lang racket
(require racket/cmdline)
(require racket/runtime-path)
;
; apply trace parser to a stream of trace records
;
; lazy stream of all datums from the input port
(define (make-trace-stream in)
(let ([datum (read in)])
(if (not (eof-object? datum))
(stream-cons datum (make-trace-stream in))
empty-stream)))
; apply a set of trace-stat% classes to the stream of trace s-expressions
; return a trace-state struct containing the statistics of the trace
(define (map-trace stat%-set in-port)
(for/fold
([sexp-count 0])
([trace-record (in-stream (make-trace-stream in-port))])
(+ sexp-count 1)))
; apply a null set of trace-stat% classes
(define (accumulate-default-trace-stats in-port)
(map-trace null in-port))
(define (print-accumulated-default-trace-stats in-port)
(printf "s-expression count: ~a\n" (accumulate-default-trace-stats in-port)))
;;-----------------------------------------------------------------------------
;; command-line parsing
(module+ main
(print-accumulated-default-trace-stats
(command-line
#:args args
(if (null? args)
(current-input-port)
(open-input-file (first args))))))
Best regards,
-Steve
--
Steve Byan
steveb...@me.com
Littleton, MA
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