On Wed, 22 Jun 2011, John Baldwin wrote:
On Tuesday, June 21, 2011 4:58:10 pm Bruce Evans wrote:
On Tue, 21 Jun 2011, Bjoern A. Zeeb wrote:
...
vm_page.o: In function `vm_page_clear_dirty':
/sys/vm/vm_page.c:(.text+0x18d0): undefined reference to `atomic_clear_8'
/sys/vm/vm_page.c:(.text+0x18d0): relocation truncated to fit: R_MIPS_26
against `atomic_clear_8'
vm_page.o: In function `vm_page_set_validclean':
/sys/vm/vm_page.c:(.text+0x38f0): undefined reference to `atomic_clear_8'
/sys/vm/vm_page.c:(.text+0x38f0): relocation truncated to fit: R_MIPS_26
against `atomic_clear_8'
Atomic types shorter than int cannot be used in MI code, since they might
not exist. Apparently they don't exist on mips. jake@ fixed all their
old uses for sparc4 in ~Y2K.
I agree. Is there any harm in having the 'dirty' and 'valid' fields in
vm_page always be at least of size 'int'?
In the case of amd64, vm_page would change from a size of 120 bytes to 128.
On i386 I think you'd end up changing the size from 68 to 76.
(Using an int results in alignment padding after 'busy'.)
That is quite a bit. Perhaps the struct should be packed better so that
each char -> int expansion takes <= 3 bytes instead of >= 4. The
expansion might even be negative. It is only moderately well packed now.
Hmm, that's around 120k of extra vm_page_t space for a machine with 64M of
RAM, so around 0.18% of RAM would be used on both platforms (presumably the
usage would be similar on other platforms as well). At 24 GB of RAM, the
extra space is just under 0.20% of RAM (48M).
Bruce
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