don't deadlock when cwgrow() detects we'r out of worm space
by releasing the cache superblock buffer.
don't allocate space beyond the worm device when dumping by
having slit() check. after cwrecur(), we check if there are
enougth blocks remaining to write the dump date directories
and superblocks.
- no need to splhi() in timerset, always called with
interrupts off.
- make timerset always update the period (next == 0)
- remove period update in fastticks(), simplify
delta calculation.
given that we only pass uchar* with constant offsets
to the s and d arguments of ENCRYPT(), we do not need
the temporary variables sp/dp and the compiler is
smart enougth to combine the const offset with the ones
from GET4() and PUT4() and emit single load and store
instructions for the byte accesses.
introducing new ctrunc() function that invalidates any caches
for the passed in chan, invoked when handling wstat with a
specified file length or on file creation/truncation.
test program to reproduce the problem:
#include <u.h>
#include <libc.h>
#include <libsec.h>
void
main(int argc, char *argv[])
{
int fd;
Dir *d, nd;
fd = create("xxx", ORDWR, 0666);
write(fd, "1234", 4);
d = dirstat("xxx");
assert(d->length == 4);
nulldir(&nd);
nd.length = 0;
dirwstat("xxx", &nd);
d = dirstat("xxx");
assert(d->length == 0);
fd = open("xxx", OREAD);
assert(read(fd, (void*)&d, 4) == 0);
}
allocating AX,CX,DX last improves 64-bit multiplication-add
chains like a*b + c*d as the multiplication does not need to save
and restore AX and DX registers in most cases. reserving CX for
shifts also helps.
encode printable characters litteraly, use D() macro to
reduce DATA instruction overhead.
this halves the time spend assembling $CONF.root.s for
the kernel build.
the root fileserver is mounted with the mount cache enabled
causing the contents of the cfsctl file to be cached as well
leading to wrong results. so after we generated the new stat
buffer, we increment the qid.vers so the cache starts out
clean.
given that the igfx driver doesnt provide any acceleration functions
and drawing is usually faster with double buffering as it eleminates
reads over the pci bus, enable softscreen by default.
