Date: Thu, 28 Mar 2002 16:46:45 -0500 From: Alexander Kabaev <ak03@gte.com> To: "Brian F. Feldman" <green@FreeBSD.ORG> Cc: arch@FreeBSD.ORG Subject: Re: vnode::v_op bugfix / PERFORCE change 8574 for review (fwd) Message-ID: <20020328164645.790f6247.ak03@gte.com> In-Reply-To: <200203281929.g2SJTBW04780@green.bikeshed.org> References: <200203281929.g2SJTBW04780@green.bikeshed.org>
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This fix will not work when/if the VFS layer will become preemptable. It also introduces potential performance penalty due to the additional pointer dereference and associated cache misses on each vnode operation. I have alternative patch which simple overallocates space for vop_t vectors a bit in order to avoid the need to realocate them and panics when this space becomes exausted. The amount of space kernel is preallocating is configurable through boot-time tunable. You can find patch at http://kan.dnsalias.net:8080/kan/tunable_vops.diff. This still needs some rewriting but it should be good enough to give you an idea on what I am proposing. There is also a patch which implement additional indirection the same way Brian's patch is doing, but tries to hide the change from the rest of the kernel code, so that operations like vp->v_op = ufs_specop_p need not be modified in existing code. The URL for the second patch is http://kan.dnsalias.net:8080/kan/indirect_vop_t.diff To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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