Date: Tue, 03 Apr 2001 09:18:07 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Alfred Perlstein <alfred@FreeBSD.org> Cc: cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: RE: cvs commit: src/sys/sys mbuf.h src/sys/kern uipc_mbuf.c Message-ID: <XFMail.010403091807.jhb@FreeBSD.org> In-Reply-To: <200104030315.f333FCX69312@freefall.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 03-Apr-01 Alfred Perlstein wrote: > alfred 2001/04/02 20:15:12 PDT > > Modified files: > sys/sys mbuf.h > sys/kern uipc_mbuf.c > Log: > Use only one mutex for the entire mbuf subsystem. > > Don't use atomic operations for the stats updating, instead protect > the counts with the mbuf mutex. Most twiddling of the stats was > done right before or after releasing a mutex. By doing this we > reduce the number of locked ops needed as well as allow a sysctl > to gain a consitant view of the entire stats structure. > > In the future... > > This will allow us to chain common mbuf operations that would > normally need to aquire/release 2 or 3 of the locks to build an > mbuf with a cluster or external data attached into a single op > requiring only one lock. > > Simplify the per-cpu locks that are planned. > > There's also some if (1) code that should check if the "how" > operation specifies blocking/non-blocking behavior, we _could_ make > it so that we hold onto the mutex through calls into kmem_alloc > when non-blocking requests are made, but for safety reasons we > currently drop and reaquire the mutex around the calls. > > Also, note that calling kmem_alloc is rare and only happens during > a shortage so drop/re-getting the mutex will not be a common > occurance. It is perfectly safe to drop the lock so long as the mbuf subsystem is in a consistent state before calling kmem_alloc(). > Remove some #define's that seemed to obfuscate the code to me. > > Remove an extranious comment. > > Remove an XXX, including mutex.h isn't a crime. Yes it is, and is going away soon. :) It will also be leaving other headers such as sys/ucred.h, sys/resourcevar.h, etc. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.010403091807.jhb>