We are not going to merge to master until Go 1.16 cycle. The old
object support can go now.
Change-Id: I93e6f584974c7749d0a0c2e7a96def35134dc566
Reviewed-on: https://go-review.googlesource.com/c/go/+/231918
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
QueryPattern will now look up the current version of a module (if any)
before invoking queryProxy. This changes the interpretation of some
patterns (like "upgrade") and avoids the need to download earlier
versions for earlier versions when the current version is
+incompatible.
Fixes#37574
Change-Id: I4089d6099236493df13a7f88a252b5e5e556d383
Reviewed-on: https://go-review.googlesource.com/c/go/+/231599
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Minor cleanup: remove a couple of unused routines, and rename
elfWriteDynEntSym2 to elfWriteDynEntSym.
Change-Id: I7c767fd4aa18d04a469be5cb1cfbe63ebe570c83
Reviewed-on: https://go-review.googlesource.com/c/go/+/231897
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Introduces a few casts, mostly to fix rules that mix int64 and int32
off1 and off2.
Passes
GOARCH=arm64 gotip build -toolexec 'toolstash -cmp' -a std
Change-Id: I1ec75211f3bb8e521dcc5217cf29ab0655a84d79
Reviewed-on: https://go-review.googlesource.com/c/go/+/230840
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The function Abbrevs() was returning an array of structures by value,
which is not very efficient (this was showing up in a kubernetes
kubelet linker profile). Switch the function to return a slice
instead.
Improves linker DwarfGenerateDebugSyms running time when
linking the compiler in compilebench:
DwarfGenerateDebugSyms 29.2ms ±144% 23.9ms ±125% -17.89% (p=0.000 n=99+99)
Change-Id: I1132816563f208c63eb82a7932d9f2bcb2455324
Reviewed-on: https://go-review.googlesource.com/c/go/+/231558
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
CL 208617 introduced syscall.utf16PtrToString and
internal/syscall/windows.UTF16PtrToString functions.
Original version of CL 208617 did not include syscall.utf16PtrToString
and internal/syscall/windows.UTF16PtrToString max parameter. The
parameter was added by Brad at the request of Ian. Ian said:
"In some cases it seems at least possible that the null terminator is
not present. I think it would be safer if we passed a maximum length
here."
The syscall.utf16PtrToString and
internal/syscall/windows.UTF16PtrToString function are designed to work
with only null terminated strings. So max parameter is superfluous.
This change removes max parameter.
Updates #34972
Change-Id: Ifea65dbd86bca8a08353579c6b9636c6f963d165
Reviewed-on: https://go-review.googlesource.com/c/go/+/228858
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
When forwarding a request, a SingleHostReverseProxy appends the
request's path to the target URL's path. However, if certain path
elements are encoded, (such as %2F for slash in either the request or
target path), simply joining the URL.Path elements is not sufficient,
since the field holds the decoded path.
Since 87a605, the RawPath field was added which holds a decoding
hint for the URL. When joining URL paths, this decoding hint needs
to be taken into consideration.
As an example, if the target URL.Path is /a/b, and URL.RawPath
is /a%2Fb, joining the path with /c should result in /a/b/c
in URL.Path, and /a%2Fb/c in RawPath.
The added joinURLPath function combines the two URL's Paths,
while taking into account escaping, and replaces the previously used
singleJoiningSlash in NewSingleHostReverseProxy.
Fixes#35908
Change-Id: I45886aee548431fe4031883ab1629a41e35f1727
GitHub-Last-Rev: 7be6b8d421
GitHub-Pull-Request: golang/go#36378
Reviewed-on: https://go-review.googlesource.com/c/go/+/213257
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This makes the intent clearer, allows for another ellipsis and will aid
in future rewriting. While here, document boolean loads to explain register
contents.
Change-Id: I933db2813826d88819366191fbbea8fcee5e4dda
Reviewed-on: https://go-review.googlesource.com/c/go/+/230120
Reviewed-by: Keith Randall <khr@golang.org>
Ctty was always handled as a child descriptor, but in some cases
passing a parent descriptor would also work. This depended on
unpredictable details of the implementation. Reject those cases to
avoid confusion.
Also reject setting both Setctty and Foreground, as they use Ctty
in incompatible ways. It's unlikely that any programs set both fields,
as they don't make sense together.
Fixes#29458
Change-Id: Ieba2d625711fd4b82c8e65e1feed02fd1fb25e6d
Reviewed-on: https://go-review.googlesource.com/c/go/+/231638
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Normalization of number prefixes and exponents was added in CL 160184
directly in cmd/gofmt. The same behavior change needs to be applied in
the go/format package. This is done by moving the normalization code
into go/printer, behind a new StdFormat mode, which is then re-used
by both cmd/gofmt and go/format.
Note that formatting of Go source code changes over time, so the exact
byte output produced by go/printer may change between versions of Go
when using StdFormat mode. What is guaranteed is that the new formatting
is equivalent Go code.
Clients looking to format Go code with standard formatting consistent
with cmd/gofmt and go/format would need to start using this flag, but
a better alternative is to use the go/format package instead.
Benchstat numbers on go test go/printer -bench=BenchmarkPrint:
name old time/op new time/op delta
Print-8 4.56ms ± 1% 4.57ms ± 0% ~ (p=0.700 n=3+3)
name old alloc/op new alloc/op delta
Print-8 467kB ± 0% 467kB ± 0% ~ (p=1.000 n=3+3)
name old allocs/op new allocs/op delta
Print-8 17.2k ± 0% 17.2k ± 0% ~ (all equal)
That benchmark data doesn't contain any numbers that need to be
normalized. More work needs to be performed when formatting Go code
with numbers, but it is unavoidable to produce standard formatting.
Fixes#37476.
For #37453.
Change-Id: If50bde4035c3ee6e6ff0ece5691f6d3566ffe8d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/231461
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Adding the usage of PCALIGN directive for arm64, and updating some
details on using some directives defined in the textflag.h file.
Change-Id: I43d363e3337939bab69b856831caf06803a292d2
Reviewed-on: https://go-review.googlesource.com/c/go/+/227801
Reviewed-by: Cherry Zhang <cherryyz@google.com>
CL 231397 is submitted too fast... Expand the comment to make it
a little clearer.
Change-Id: Ica9737aa7b51f97320bab74457388dcab8188370
Reviewed-on: https://go-review.googlesource.com/c/go/+/231597
Reviewed-by: Austin Clements <austin@google.com>
This commit adds a new option to the x86 assembler. If the
GOAMD64 environment variable is set to alignedjumps (the
default) and we're doing a 64 bit build, the assembler will
make sure that neither stand alone nor macro-fused jumps will
end on or cross 32 byte boundaries. To achieve this, functions
are aligned on 32 byte boundaries, rather than 16 bytes, and
jump instructions are padded to ensure that they do not
cross or end on 32 byte boundaries. Jumps are padded
by adding a NOP instruction of the appropriate length before
the jump.
The commit is likely to result in larger binary sizes when
GOAMD64=alignedjumps. On the binaries tested so far, an
increase of between 1.4% and 1.5% has been observed.
Updates #35881
Co-authored-by: David Chase <drchase@google.com>
Change-Id: Ief0722300bc3f987098e4fd92b22b14ad6281d91
Reviewed-on: https://go-review.googlesource.com/c/go/+/219357
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
A symbol being reachable doesn't imply its type descriptor is
needed. Don't mark it.
If the type is converted to interface somewhere in the program,
there will be an explicit use of the type descriptor, which
will make it marked.
A println("hello") program before and after
-rwxr-xr-x 1 cherryyz primarygroup 1259824 Apr 30 23:00 hello
-rwxr-xr-x 1 cherryyz primarygroup 1169680 Apr 30 23:10 hello
Updates #38782.
Updates #6853.
Change-Id: I88884c126ce75ba073f1ba059c4b892c87d2ac96
Reviewed-on: https://go-review.googlesource.com/c/go/+/231397
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
(Reland of golang.org/cl/33677.)
This CL adds a UsesCgo config setting to go/types to specify that the
_cgo_gotypes.go file generated by cmd/cgo has been provided as a
source file. The type checker then internally resolves C.bar qualified
identifiers to _Cfoo_bar as appropriate.
It also adds support to srcimporter to automatically run cgo.
Unfortunately, this functionality is not compatible with overriding
OpenFile, because cmd/cgo and gcc will directly open files.
Updates #16623.
Updates #35721.
Change-Id: Ib179d55c8c589916f98ceeae0b9a3e746157253a
Reviewed-on: https://go-review.googlesource.com/c/go/+/231459
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Cgo's initial design for handling "#define foo int*" involved
rewriting "C.foo" to "*_Ctype_int" everywhere. But now that we have
type aliases, we can declare "type _Ctype_foo = *_Ctype_int" once, and
then rewrite "C.foo" to just "_Ctype_foo".
This is important for go/types's UsesCgo mode, where go/types needs to
be able to figure out a type for each C.foo identifier using only the
information written into _cgo_gotypes.go.
Fixes#38649.
Change-Id: Ia0f8c2d82df81efb1be5bc26195ea9154c0af871
Reviewed-on: https://go-review.googlesource.com/c/go/+/230037
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
For latest http2 changes.
Which then required updating golang.org/x/sys in cmd too.
Change-Id: I3fac5f3a15f4c9381baaff597873ed0c6209dbac
Reviewed-on: https://go-review.googlesource.com/c/go/+/231457
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Add code to the loader to enforce the invariant that there is only a
single level of 'outer' symbol nesting. That is, if outer(X) = Y, then
outer(Y) is always zero.
Revise foldSubSymbolOffset based on the new invariant, allowing it to
be inlined, and then fix the various "for s.Outer != nil" loops in the
linker to just use an "if" instead of a loop.
Change-Id: Ib895702bc6de52718248f09a5368b84cb2e0a3fa
Reviewed-on: https://go-review.googlesource.com/c/go/+/231137
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Refer to reflect.StringHeader in the godoc comment for type String
instead of reflect.SliceHeader.
Change-Id: I40fc016c7365510a12c41d4ca596f66d2892c3f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/231537
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
In the dev.link branch we continued developing the new object
file format support and the linker improvements described in
https://golang.org/s/better-linker . Since the last merge, more
progress has been made to improve the new linker, with
improvements on both linker speed and memory usage.
This is a clean merge.
Change-Id: I38516d6c4b41021bc61c1b9886e701de5fa2b0f1
Convert the part that uses relocations to use loader.ExtReloc
directly. It still uses sym.Symbols for now, but not sym.Relocs.
This reduces some memory usage: linking cmd/compile with external
linking,
name old allocs/op new allocs/op delta
Loadlibfull_GC 52.2MB ± 0% 13.9MB ± 0% -73.40% (p=0.008 n=5+5)
name old live-B new live-B delta
Loadlibfull_GC 75.5M ± 0% 61.9M ± 0% -18.02% (p=0.008 n=5+5)
Change-Id: I317ecbf516063c42b255b2caba310ea6281342d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/231319
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
For now this will only avoid copying math/big/arith_riscv64.s
Change-Id: Ib236e4bf1a6a758649629268a6f512f307596e74
Reviewed-on: https://go-review.googlesource.com/c/go/+/231298
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reduces binary size by 4K, not counting the http2 changes (in CL
231119) that'll be bundled into this package in the future.
Updates golang/go#38782
Change-Id: Id360348707e076b8310a8f409e412d68dd2394b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/231118
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The Ctty field is a child descriptor number when Setctty is set,
but a parent descriptor when Foreground is set. This is absurd
but changing either behavior breaks existing programs.
With this change we at least document how it works.
For #29458
Change-Id: If9cf0a1a1e6ed0d4a4edae5043016d5b4ee3308b
Reviewed-on: https://go-review.googlesource.com/c/go/+/229768
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Implement special case handling and testing to ensure
conformance with the C99 standard annex G.6 Complex arithmetic.
Fixes#29320
Change-Id: Id72eb4c5a35d5a54b4b8690d2f7176ab11028f1b
Reviewed-on: https://go-review.googlesource.com/c/go/+/220689
Reviewed-by: Robert Griesemer <gri@golang.org>
The new package "internal/unsafeheader" depends only on "unsafe", and
provides declarations equivalent to reflect.StringHeader and
reflect.SliceHeader but with Data fields of the proper unsafe.Pointer
type (instead of uintptr).
Unlike the types it replaces, the "internal/unsafeheader" package has
a regression test to ensure that its header types remain equivalent to
the declarations provided by the "reflect" package.
Since "internal/unsafeheader" has almost no dependencies, it can be
used in other low-level packages such as "syscall" and "reflect".
This change is based on the corresponding x/sys change in CL 231177.
Fixes#37805
Updates #19367
Change-Id: I7a6d93ef8dd6e235bcab94e7c47270aad047af31
Reviewed-on: https://go-review.googlesource.com/c/go/+/231223
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Now that the loader's internal storage mechanism for symbol alignment
is array-based and not map-based, we can go back to computing symbol
alignment in the parallel-by-section section of dodata.
With this patch plus the previous one, this produces a small
kubelet speedup:
$ benchstat out.devlink.txt out.align.txt
name old time/op new time/op delta
RelinkKubelet 13.3s ± 2% 13.1s ± 2% -1.27% (p=0.000 n=20+20)
RelinkKubelet-WithoutDebug 7.36s ± 5% 7.14s ± 3% -3.00% (p=0.000 n=20+20)
Change-Id: I9eb0e8fea6aeb12f188f499e9031d5a3a23232c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/231221
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Switch the storage mechanism for symbol alignment away from a map and
to a slice of uint8 values per symbol, where value K indicates
alignment 2^K. Intended to help speed up alignment get/set in dodata.
Change-Id: I26416e455c808f697dd0d7f6d2582247ee5c5b40
Reviewed-on: https://go-review.googlesource.com/c/go/+/231220
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Using 'go get x.go' instead of 'go build x.go' or some other
go command is a common mistake. By that mistake, a user gets
a misleading error message about unsuccessful `x.go` domain lookup.
This improvement handles such cases, by validating, whether the
argument hasn't specified version, has .go suffix, and either has
no slashes or such file locally exists. Handled both GOPATH
and GOMOD modes.
Fixes#38478
Change-Id: I583a4ef7f7ca8901deb07ebc811e2b3c0e828fa6
Reviewed-on: https://go-review.googlesource.com/c/go/+/229938
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
parseFloatPrefix accepts a string if it has a valid floating-point
number as prefix. Make sure that "infi", "infin", ... etc. are
accepted as valid numbers "inf" with suffix "i", "in", etc. This
is important for parsing complex numbers such as "0+infi".
This change does not affect the correctness of ParseFloat because
ParseFloat rejects strings that contain a suffix after a valid
floating-point number.
Updates #36771.
Change-Id: Ie1693a8ca2f8edf07b57688e0b35751b7100d39d
Reviewed-on: https://go-review.googlesource.com/c/go/+/231237
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently, for external relocations, the ExtReloc structure
contains all the fields of the relocation. In fact, many of the
fields are the same with the original relocation. So, instead, we
can just use an index to reference the original relocation and
not expand the fields.
There is one place where we modify relocation type: changing
R_DWARFSECTREF to R_ADDR. Get away with it by changing
downstreams.
It also makes it easier to retrieve the reloc variant.
This reduces some allocation. Linking cmd/compile with external
linking,
name old alloc/op new alloc/op delta
Reloc_GC 34.1MB ± 0% 22.7MB ± 0% -33.30% (p=0.000 n=5+4)
Change-Id: Id08a89ed2aee705296886d3b95014b806a0d55cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/231217
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
In the dev.link branch we continued developing the new object
file format support and the linker improvements described in
https://golang.org/s/better-linker . Since the last merge, more
progress has been made to improve the new linker.
This is a clean merge.
Change-Id: Ide5ad6fcec9cede99e9b21c4548929b4ba1f4185
Revise the signature for "relocsym" to reflect the fact that many of
its arguments are invariant: push the invariant args into a struct and
pass the struct by reference.
Add a facility for doing batch allocation of external relocations in
relocsym, so that we don't wind up with wasted space due to the
default "append" behavior.
This produces a small speedup in linking kubelet:
$ benchstat out.devlink.txt out.dodata.txt
name old time/op new time/op delta
RelinkKubelet 14.2s ± 2% 13.8s ± 2% -3.11% (p=0.000 n=19+19)
RelinkKubelet-WithoutDebug 8.02s ± 3% 7.73s ± 3% -3.67% (p=0.000 n=20+20)
Change-Id: I8bc94c366ae792a5b0f23697b8e0108443a7a748
Reviewed-on: https://go-review.googlesource.com/c/go/+/231138
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Under the scavenge lock it's possible to ready a goroutine (or now
injectglist, which has mostly the same effect) which could cause an
unpark trace event to be emitted. If there's no active trace buffer for
the P, then we might acquire the lock. The total order between the two
is correct, but there's no partial order edge between them. Add in the
edge.
Change-Id: I3fc5d86a3b6bdd0b5648181fb76b5ebc90c3d69f
Reviewed-on: https://go-review.googlesource.com/c/go/+/231197
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
This change modifies the semantics of waking the scavenger: rather than
wake on any update to pacing, wake when we know we will have work to do,
that is, when the sweeper is done. The current scavenger runs over the
address space just once per GC cycle, and we want to maximize the chance
that the scavenger observes the most attractive scavengable memory in
that pass (i.e. free memory with the highest address), so the timing is
important. By having the scavenger awaken and reset its search space
when the sweeper is done, we increase the chance that the scavenger will
observe the most attractive scavengable memory, because no more memory
will be freed that GC cycle (so the highest scavengable address should
now be available).
Furthermore, in applications that go idle, this means the background
scavenger will be awoken even if another GC doesn't happen, which isn't
true today.
However, we're unable to wake the scavenger directly from within the
sweeper; waking the scavenger involves modifying timers and readying
goroutines, the latter of which may trigger an allocation today (and the
sweeper may run during allocation!). Instead, we do the following:
1. Set a flag which is checked by sysmon. sysmon will clear the flag and
wake the scavenger.
2. Wake the scavenger unconditionally at sweep termination.
The idea behind this policy is that it gets us close enough to the state
above without having to deal with the complexity of waking the scavenger
in deep parts of the runtime. If the application goes idle and sweeping
finishes (so we don't reach sweep termination), then sysmon will wake
the scavenger. sysmon has a worst-case 20 ms delay in responding to this
signal, which is probably fine if the application is completely idle
anyway, but if the application is actively allocating, then the
proportional sweeper should help ensure that sweeping ends very close to
sweep termination, so sweep termination is a perfectly reasonable time
to wake up the scavenger.
Updates #35788.
Change-Id: I84289b37816a7d595d803c72a71b7f5c59d47e6b
Reviewed-on: https://go-review.googlesource.com/c/go/+/207998
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change adds two bits of logic to the scavenger's pacing. Firstly,
it checks to make sure we scavenged at least one physical page, if we
released a non-zero amount of memory. If we try to release less than one
physical page, most systems will release the whole page, which could
lead to memory corruption down the road, and this is a signal we're in
this situation.
Secondly, the scavenger's pacing logic now checks to see if the time a
scavenging operation takes is measured to be exactly zero or negative.
The exact zero case can happen if time update granularity is too large
to effectively capture the time the scavenging operation took, like on
Windows where the OS timer frequency is generally 1ms. The negative case
should not happen, but we're being defensive (against kernel bugs, bugs
in the runtime, etc.). If either of these cases happen, we fall back to
Go 1.13 behavior: assume the scavenge operation took around 10µs per
physical page. We ignore huge pages in this case because we're in
unknown territory, so we choose to be conservative about pacing (huge
pages could only increase the rate of scavenging).
Currently, the scavenger is broken on Windows because the granularity of
time measurement is around 1 ms, which is too coarse to measure how fast
we're scavenging, so we often end up with a scavenging time of zero,
followed by NaNs and garbage values in the pacing logic, which usually
leads to the scavenger sleeping forever.
Fixes#38617.
Change-Id: Iaaa2a4cbb21338e1258d010f7362ed58b7db1af7
Reviewed-on: https://go-review.googlesource.com/c/go/+/229997
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Austin Clements <austin@google.com>
