The idea is:
When we call sched() with interrupts disabled,
it must not return with them re-enabled.
The code becomes easier to reason about if
we make sched() preserve interrupt status,
which lets us call sched() from an interrupt
handler (with interrupts disabled) without
risking preemption by another interrupt once
sched() returns which can pump-up the stack.
This allows removing Proc.preempted flag as
it is now impossible for interrupts to
preempt each other in preempted().
Extra cleanups:
make interrupted() _Noreturn void
and remove unused Proc.yield flag.
the symptom is that ping is apparently skipping
transmits which recover with the next send,
resulting in exactly send-period spikes in
the ping rtt.
It appears that the core seems to reorder writes
to uncached memory, which can result in the doorbell
being written before the descriptor status bits
are written.
put a coherence() barrier before writing doorbell
fixes it.
thanks sigrid for reporting the issue!
On a multiprocessor, the scheduler can run into
a very unfair distribution of processes to cpus
when there are more long-running processes than cpus.
Say we have a 4 cpu machine and we run 4 long-running
proesses, each cpu will pick up a single process
and each process will get 100% of its fair share.
Everything is good so far.
If we start more long-running processes, all these
processes are going to be picked up by the cpu core
that runs most sporanic / bursty work loads as it
is calling sched() more often.
This results in all the extra long-running prcoesses
to cluster around the same core resulting in very
unfair sharing of load.
The problem is that once a process runs on a cpu,
it stays on that cpu as processor affinity
is never reset.
Process migration only happens when a cpu cannot
find any process to run, given the affinity
constrains, but this can never happen when
the system is under full load and each cpu
always has a low-priority long running
process to run.
How do we fix this?
The idea of this hack is to reset processor
affinity in ready() when its priority changes or,
when it appears to be a long-running process.
That way, we give every cpu a chance to pick
it up and share the load.
This is not a ideal solution of course. Long term,
we should probably have separate runqueues per cpu
and do the balancing explicitely.
In the sched() function, the call to reprioritize()
must be done before we set up, as reprioritize()
calls updatecpu(), which determines if the process
was running or not based on p == up. So move
the call to runproc() itself.
while rehashing the same files over and over will work
just fine, it can be slow with a large number of large
files; this makes 'git/comit .' perform much better in
repos with a large number of large binary blobs.
compress when the log doubles in size, rather than
using a fixed size heuristic; this means that we
don't start compressing frequently as the log gets
big and the file system gets fragmented.
this happens in libframe:
/sys/src/libframe/frutil.c:80: x -= (x-f->r.min.x)%f->maxtab;
but there's no way to control when the user changes the
maxtab value, so it's samterm's responsibility to
sanitize it.
we were copying the owner and group of the parent dir into the fid
on create, but we forgot the mode; fix that, so that we don't check
perms against the wrong dir.
The Italian keyboard layout is ISO, and unlike the ANSI layout,
it has an extra key between Shift and Z, and the key above Enter,
which becomes vertical, is moved to the bottom left of it.
- the key between Shift and Z is mapped to `<`, and shift+`<` is mapped to `>`
- the old `>` (at the bottom left of Enter) is mapped to `ù`
- shift+`ù` is mapped to `§`
- the old shift+`"` is mapped to `°`
- altgr+`'` is mapped to backtick
- altgr+`ì` is mapped to `~`
- altgr+`e` is mapped to `€`
- shiftaltgr+`[` is mapped to `{`
- shiftaltgr+`]` is mapped to `}`
This seems to have been around but not compiled since the third edition.
Remove it and the accompanying SMBus machinery that is only used
for this driver.
When modifying a sparse file, it's possible to get
clobbers and clears to item s that don't exist; in
this case, we try to apply to an empty kvp, and
assert -- we should just not apply.
void
main(void)
{
uchar a[3];
float f = a[2] | a[1] | (a[0]/1.2);
USED(f);
}
the code above used to generate impossible
code in the linker like:
main: doasm: notfound from=34 to=35 (872) ORL X0,X1
main: doasm: notfound from=34 to=35 (872) ORL X0,X1
main: doasm: notfound from=34 to=35 (872) ORL X0,X1
with the change, the compiler correctly rejects it:
incompatible types: "UINT" and "DOUBLE" for op "OR"
i assume the BNUMBER in the type matrix must have been
a oversight.
do not add default route when address is
deprecated (preflt == 0).
delete previous default route on router change.
implement rfc4862 section 5.5.3 processing rules
in regard to remaining valid lifetime.
In addition to removing expired default routes,
ask devip to clean out expired addresses as well.
In the future, devip might do something more
sophisticated than just checking the valid life time
like also considering if the address is still begin
used by active connections.
we shouldn't need to defer reclamation for procs that
don't actually interact with the tree directly, especially
since if they send on a channel they can stall for a while.
This change covers three improvements:
- inline the limbo entry into the objects
being freed, meaning we don't need to
allocate, and thus can't fail to free
an object when we're out of memory
- Preallocate Bfree objects, for the same
reason above.
the build process could be cleaned up a lot more. the default.*.h headers are
basically only used in cross-compilation, but every usable arch has its default
header already, so all the mkfile effectively does is copy it to $objtype.h. it
would perhaps make more sense to just run mk on any new arch and copy to a new
default.$objtype.h and get rid of a lot of this stuff. but then it's not really
worth messing with this further, so leaving it as is.
We were inserting very oversized deletion messages when
removing a file, instead of inserting the right size
message. This also batches the insertions, reducing the
number of upserts.
