sync/atomic: fix ARM nomenclature in comments

R=cshapiro
CC=golang-dev
https://codereview.appspot.com/12877043
runtime: fix false deadlock crash
Fixes issue 6070.
Update issue 6055.

R=golang-dev, nightlyone, rsc
CC=golang-dev
https://codereview.appspot.com/12602043
runtime: do no lose CPU profiling signals
Currently we lose lots of profiling signals.
Most notably, GC is not accounted at all.
But stack splits, scheduler, syscalls, etc are lost as well.
This creates seriously misleading profile.
With this change all profiling signals are accounted.
Now I see these additional entries that were previously absent:
161  29.7%  29.7%      164  30.3% syscall.Syscall
 12   2.2%  50.9%       12   2.2% scanblock
 11   2.0%  55.0%       11   2.0% markonly
 10   1.8%  58.9%       10   1.8% sweepspan
  2   0.4%  85.8%        2   0.4% runtime.newstack
It is still impossible to understand what causes stack splits,
but at least it's clear how many time is spent on them.
Update issue 2197.
Update issue 5659.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/12179043
runtime: more reliable preemption
Currently it's possible that a goroutine
that periodically executes non-blocking
cgo/syscalls is never preempted.
This change splits scheduler and syscall
ticks to prevent such situation.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/12658045
runtime: fix LockOSThread
Fixes issue 6100.

R=golang-dev, dave, bradfitz, rsc
CC=golang-dev
https://codereview.appspot.com/12703045
undo CL 12787044 / ed695cdf962b

The NetBSD and OpenBSD failures are apparently real,
not due to the test bug fixed in 100b9fc0c46f.

««« original CL description
runtime/pprof: test netbsd and openbsd again

Maybe these will work now.

R=golang-dev, dvyukov, bradfitz
CC=golang-dev
https://codereview.appspot.com/12787044
»»»

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12873043

Committer: Dmitriy Vyukov <dvyukov@google.com>
runtime: tell GC not to scan internal hashmap structures.
We'll do it ourselves via hash_gciter, thanks.
Fixes bug 6119.

R=golang-dev, dvyukov, cookieo9, rsc
CC=golang-dev
https://codereview.appspot.com/12840043
undo CL 12840043 / 3b9f54db72a1

Breaks the build.  Old bucket arrays kept by iterators
still need to be scanned.

««« original CL description
runtime: tell GC not to scan internal hashmap structures.
We'll do it ourselves via hash_gciter, thanks.
Fixes bug 6119.

R=golang-dev, dvyukov, cookieo9, rsc
CC=golang-dev
https://codereview.appspot.com/12840043
»»»

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/12884043
sync/atomic: update comment for ARM 64-bit atomics

They don't work on older chips, just like the x86-32 64-bit atomics.

Update issue 6134

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12880043
runtime: dump scheduler state if GODEBUG=schedtrace is set
The schedtrace value sets dump period in milliseconds.
In default mode the trace looks as follows:
SCHED 0ms: gomaxprocs=4 idleprocs=0 threads=3 idlethreads=0 runqueue=0 [1 0 0 0]
SCHED 1001ms: gomaxprocs=4 idleprocs=3 threads=6 idlethreads=3 runqueue=0 [0 0 0 0]
SCHED 2008ms: gomaxprocs=4 idleprocs=1 threads=6 idlethreads=1 runqueue=0 [0 1 0 0]
If GODEBUG=scheddetail=1 is set as well, then the detailed trace is printed:
SCHED 0ms: gomaxprocs=4 idleprocs=0 threads=3 idlethreads=0 runqueue=0 singleproc=0 gcwaiting=1 mlocked=0 nmspinning=0 stopwait=0 sysmonwait=0
  P0: status=3 tick=1 m=0 runqsize=1/128 gfreecnt=0
  P1: status=3 tick=0 m=-1 runqsize=0/128 gfreecnt=0
  P2: status=3 tick=0 m=-1 runqsize=0/128 gfreecnt=0
  P3: status=3 tick=0 m=-1 runqsize=0/128 gfreecnt=0
  M2: p=-1 curg=-1 mallocing=0 throwing=0 gcing=0 locks=1 dying=0 helpgc=0 spinning=0 lockedg=-1
  M1: p=-1 curg=-1 mallocing=0 throwing=0 gcing=0 locks=1 dying=0 helpgc=0 spinning=0 lockedg=-1
  M0: p=0 curg=1 mallocing=0 throwing=0 gcing=0 locks=1 dying=0 helpgc=0 spinning=0 lockedg=1
  G1: status=2() m=0 lockedm=0
  G2: status=1() m=-1 lockedm=-1

R=golang-dev, raggi, rsc
CC=golang-dev
https://codereview.appspot.com/11435044
net: fix windows build
Windows builders say:
pkg\net\dnsclient_unix_test.go:24: undefined: dnsConfig
pkg\net\dnsclient_unix_test.go:25: undefined: exchange

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/12889043
net: fix build fix
Now builders say:
pkg/net/dnsclient_unix_test.go:10: imported and not used: "runtime"

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/12890043
cmd/go: nicer error diagnosis in go test
Before,
        go test -bench .
would just dump the long generic "go help" message. Confusing and
unhelpful. Now the message is short and on point and also reminds the
user about the oft-forgotten "go help testflag".

        % go test -bench
        go test: missing argument for flag bench
        run "go help test" or "go help testflag" for more information
        %

R=rsc
CC=golang-dev
https://codereview.appspot.com/12662046
encoding/binary: make Write work like Read
Use the fast path calculation to shorten the code.
No effect on benchmarks.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/12696046
archive/zip: remove an allocation, speed up a test

Update Issue 6138

TestOver65kFiles spends all its time garbage collecting.
Removing the 1.4 MB of allocations per each of the 65k
files brings this from 34 seconds to 0.23 seconds.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/12894043
database/sql: add a disabled broken test

Update issue 6081

R=golang-dev, gri
CC=golang-dev
https://codereview.appspot.com/12810043
net: make Dial, Listen and ListenPacket return consistent error value

Update issue 4856

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/12763044
archive/zip: add File.DataOffset

Accessor to find where the bytes of a file start.

R=golang-dev, rsc, dsymonds, adg
CC=golang-dev
https://codereview.appspot.com/12784045
runtime: fix build on arm

Do not use ? :
I cannot say this enough.

TBR=dvyukov
CC=golang-dev
https://codereview.appspot.com/12903043
cmd/go: add -t flag to 'go get' to download test dependencies

Fixes issue 5126.

R=golang-dev, dsymonds, bradfitz, r, rsc, rogpeppe
CC=golang-dev
https://codereview.appspot.com/12566046