Date: Sun, 06 Jan 2008 21:13:22 -0800 From: Xin LI <delphij@delphij.net> To: freebsd-arch@FreeBSD.org Cc: dfr@FreeBSD.org, mengguang@staff.sina.com.cn Subject: Why it does not make sense if msginfo.msgssz is greater than 256? Message-ID: <4781B4F2.9040707@delphij.net>
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Hi,
While pursuing sys/kern/sysv_msg.c, we found the following comment:
* Each message is broken up and stored in segments that are msgssz bytes
* long. For efficiency reasons, this should be a power of two. Also,
* it doesn't make sense if it is less than 8 or greater than about 256.
* Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of
* two between 8 and 1024 inclusive (and panic's if it isn't).
And it seems to be come from the following comment:
/*
* msginfo.msgssz should be a power of two for efficiency reasons.
* It is also pretty silly if msginfo.msgssz is less than 8
* or greater than about 256 so ...
*/
Why is there the limitation (recommendation)?
Thanks in advance!
Cheers,
- --
Xin LI <delphij@delphij.net> http://www.delphij.net/
FreeBSD - The Power to Serve!
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