Date: Wed, 10 Sep 2003 08:20:47 +0200 From: Poul-Henning Kamp <phk@phk.freebsd.dk> To: arch@freebsd.org Subject: The struct buf junta met... Message-ID: <5148.1063174847@critter.freebsd.dk>
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The struct buf junta met at an undisclosed location, and this is what
we found out:
With the 5-stable branch (still) being 3-4 in the future, we want
to get as much as the API changes into the stable branch as possible,
in order to not do another "3.x mistake".
The things you can expect to see appearing (provided we can make it
work) is:
1. Move floppies & CD's under GEOM.
2. Move the vcount() to the dev_t for VCHR.
This removes one icky problem from vnode locking.
3. Vnode bypass for userland device access.
This is the stuff I posted a prototype of some time ago: Go directly
from the filedesc switch to SPECFS thus bypassing vnodes and vnode
locking intirely and going Giant-free for drivers that support this.
4. Scatter/Gather mapped/unmapped struct bio.
This allows an I/O request to be composed of a number of pages spread
out in physical memory.
5. Shoot pbufs
In swap_pager.c, vfs_cluster, spec_getpages, AIO, O_DIRECT...
We have a lot of ideas going forward from that point, but they are
not concrete enough to actually formulate as a plan yet.
We will try to explain this coherently at the devsummit this weekend
and in email subsequent to that.
Secretary for the Buf Junta
Poul-Henning
--
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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