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3e347834 |
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16-Apr-2021 |
Alexander Motin <mav@FreeBSD.org> |
pms(4): Limit maximum I/O size to 256KB instead of 1MB.
There is a weird limit of AGTIAPI_MAX_DMA_SEGS (128) S/G segments per
I/O since the initial driver import. I don't know why it was added,
can only guess some hardware limitation, but in worst case it means
maximum I/O size of 508KB. Respect it to be safe, rounding to 256KB.
MFC after: 1 week
Sponsored by: iXsystems, Inc.
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| #
cd853791 |
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27-Nov-2020 |
Konstantin Belousov <kib@FreeBSD.org> |
Make MAXPHYS tunable. Bump MAXPHYS to 1M.
Replace MAXPHYS by runtime variable maxphys. It is initialized from
MAXPHYS by default, but can be also adjusted with the tunable kern.maxphys.
Make b_pages[] array in struct buf flexible. Size b_pages[] for buffer
cache buffers exactly to atop(maxbcachebuf) (currently it is sized to
atop(MAXPHYS)), and b_pages[] for pbufs is sized to atop(maxphys) + 1.
The +1 for pbufs allow several pbuf consumers, among them vmapbuf(),
to use unaligned buffers still sized to maxphys, esp. when such
buffers come from userspace (*). Overall, we save significant amount
of otherwise wasted memory in b_pages[] for buffer cache buffers,
while bumping MAXPHYS to desired high value.
Eliminate all direct uses of the MAXPHYS constant in kernel and driver
sources, except a place which initialize maxphys. Some random (and
arguably weird) uses of MAXPHYS, e.g. in linuxolator, are converted
straight. Some drivers, which use MAXPHYS to size embeded structures,
get private MAXPHYS-like constant; their convertion is out of scope
for this work.
Changes to cam/, dev/ahci, dev/ata, dev/mpr, dev/mpt, dev/mvs,
dev/siis, where either submitted by, or based on changes by mav.
Suggested by: mav (*)
Reviewed by: imp, mav, imp, mckusick, scottl (intermediate versions)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D27225
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