Date: Fri, 23 Jan 2004 13:00:39 -0800 (PST) From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/61691: very bad performance of realloc()/brk() Message-ID: <200401232100.i0NL0d6o060310@freefall.freebsd.org>
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The following reply was made to PR kern/61691; it has been noted by GNATS. From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Radim Kolar <hsn@netmag.cz> Cc: freebsd-bugs@FreeBSD.org, bug-followup@FreeBSD.org Subject: Re: kern/61691: very bad performance of realloc()/brk() Date: Fri, 23 Jan 2004 21:51:36 +0100 In message <20040123152035.GA2311@asura.bsd>, Radim Kolar writes: >> You seem to be confused as to what responsibilities the programmer >> has when it comes to practicing sensible memory management. >I have run some benchmarks for you. There are doing 32 times realloc() in >1 MB chunks. I don't think that this is example of bad programming >practice. The major problem is that realloc() copies data while Linux >doesn't. No, as I said, the problem is you use realloc the wrong way. You should not malloc(1M) realloc(2M) realloc(3M) You should realloc(32M) do stuff realloc(now_i_know_the_size) For whatever value of 32M 99% of your data fit in. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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