Date: Fri, 20 Oct 2000 21:12:24 +0200 From: Poul-Henning Kamp <phk@freebsd.org> To: current@freebsd.org Subject: Junior Kernel Hacker Task: M_ZERO Message-ID: <17100.972069144@critter>
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I have introduced the M_ZERO flag to the kernel malloc, which provides
the service to bzero() the memory allocted.
In the kernel sources, the archetypical change to use this facility
looks like this:
Old code:
databuf = malloc(length, M_DEVBUF, M_WAITOK);
bzero(databuf, length);
New code:
databuf = malloc(length, M_DEVBUF, M_WAITOK | M_ZERO);
Short term the benefit is less clutter in the code and a smaller
cache footprint of the kernel.
Long term, this will allow us to optimize malloc(9) by allocating
from a pool of memory which is zero'ed whenever the cpu is idle.
If anybody is looking for a simple task to perform in the FreeBSD
kernel: this is it.
A quick grep tells me that there are at least 91 files in the src/sys
tree which could use this flag to simplify and optimize the code.
The ground rules for such a cleanup are:
Respect the style of the source file.
Don't make unrelated changes: If you spot other issues with
the code as you read it, make a separate diff for those issues.
Bundle the patches at administrative boundaries: a directory
at a time, a driver at a time etc etc.
Submit changes to the maintainer of the file (if any) or
with send-pr.
Junior committers are encouraged to review and commit these
PR's as they arrive
--
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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