Date: Sun, 15 Aug 2004 22:21:46 -0400 (EDT) From: Dan Ponte <dcp1990@cox.net> To: FreeBSD-gnats-submit@FreeBSD.org Cc: uau@users.sourceforge.net Subject: bin/70511: When fread()ing with buffering turned off, many syscalls invoked. Message-ID: <20040816022146.797EE409E@styx.flinkpoyd.homeunix.com> Resent-Message-ID: <200408160230.i7G2UM3h086705@freefall.freebsd.org>
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>Number: 70511 >Category: bin >Synopsis: When fread()ing with buffering turned off, many syscalls invoked. >Confidential: no >Severity: non-critical >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon Aug 16 02:30:21 GMT 2004 >Closed-Date: >Last-Modified: >Originator: Dan Ponte >Release: FreeBSD 5.2.1-RELEASE-p9 i386 >Organization: Unix Users Anonymous >Environment: System: FreeBSD styx.cox.net 5.2.1-RELEASE-p9 FreeBSD 5.2.1-RELEASE-p9 #7: Thu Jul 1 13:17:08 EDT 2004 dcp1990@styx.cox.net:/usr/obj/usr/src/sys/STYX i386 Python 2.2.2 >Description: When calling fread and buffering turned off, a read() syscall is made for each byte. With large limits, this may take a while and is very inefficient. >How-To-Repeat: In python, enter the following command: t=file('bigfile', 'r', 0).read(10000000) , replacing 'bigfile' with a large file. Notice how it takes a while to run. Now, start Python with truss and enter the same, and notice the flood of read() syscalls. >Fix: Change __srefill() in stdio to read blocks at a time, instead of one byte. >Release-Note: >Audit-Trail: >Unformatted:
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