std.os: add sysconf(), getDefaultPageSize() with smoke tests #16638

matu3ba · 2023-07-31T23:41:38Z

sysconf() abstracts posix sysconf for comptime- and runtime probing.

getDefaultPageSize() reads the Kernel provided default page size,
which remains constant from program start to end.

Closes #11308.

matu3ba · 2023-08-01T09:43:44Z

~~Looking good: As expected, besides the c symbol includes tests fail with error: 'test.getPageSize smoke test' failed: expected 4096, found 100. I'll fix up things later today.~~

REVIEW QUESTION: Should Kernel abi things reference the official repo + tagged commit? Personally, I'd prefer linking to a git reference, if an official one exists.

List of TODOs:

better name
explain usage
add this info to the commit
windows NtQuerySystemInformation since its already used and looks relative risk free
add sysconf numbers for _SC_PAGESIZE as _SC.PAGESIZE
~~make an issue to clarify if and how allocation of page sizes the kernel supports should be supported~~
followup: prepare large tables api including comment on necessary windows capabilities

Common alias for _SC_PAGE_SIZE is _SC_PAGESIZE

#!/usr/bin/env sh
git clone --depth=1 https://github.com/DragonFlyBSD/DragonFlyBSD
git clone --depth=1 https://github.com/freebsd/freebsd-src
git clone --depth=1 https://fuchsia.googlesource.com/fuchsia
git clone --depth=1 https://github.com/haiku/haiku
git clone --depth=1 https://github.com/hermitcore/rusty-hermit
git clone --depth=1 https://github.com/Stichting-MINIX-Research-Foundation/minix/
git clone --depth=1 https://github.com/NetBSD/src netbsd
git clone --depth=1 https://github.com/openbsd/src openbsd
git clone --depth=1 https://github.com/kofemann/opensolaris
rg 'define.*_SC_PAGE_SIZE' -B 1 --vimgrep

# Cleaned up output
DragonFlyBSD/include/unistd.h:240:9:#define	_SC_PAGESIZE		47
DragonFlyBSD/include/unistd.h:305:24:#define	_SC_PAGE_SIZE		_SC_PAGESIZE
freebsd-src/include/unistd.h:213#define	_SC_PAGESIZE		47
freebsd-src/include/unistd.h:278#define	_SC_PAGE_SIZE		_SC_PAGESIZE
fuchsia/zircon/third_party/ulib/musl/include/unistd.h:281:9:#define _SC_PAGE_SIZE 30
fuchsia/zircon/third_party/ulib/musl/include/unistd.h:282:9:#define _SC_PAGESIZE 30 /* !! */
haiku/headers/posix/unistd.h:187:9:#define _SC_PAGE_SIZE			27
haiku/headers/posix/unistd.h:188:9:#define _SC_PAGESIZE			_SC_PAGE_SIZE
minix/sys/sys/unistd.h:248:9:#define	_SC_PAGESIZE		28
minix/sys/sys/unistd.h:249:24:#define	_SC_PAGE_SIZE		_SC_PAGESIZE	/* 1170 compatibility */
netbsd/sys/sys/unistd.h:257:#define	_SC_PAGESIZE		28
netbsd/sys/sys/unistd.h:258:#define	_SC_PAGE_SIZE		_SC_PAGESIZE	/* 1170 compatibility */
openbsd/include/unistd.h:180:#define	_SC_PAGESIZE		28
openbsd/include/unistd.h:180:#define	_SC_PAGE_SIZE		_SC_PAGESIZE	/* 1170 compatibility */
opensolaris/usr/src/ucbhead/unistd.h:84#define	_SC_PAGESIZE	11
opensolaris/usr/src/uts/common/sys/unistd.h:182:25:#define	_SC_PAGE_SIZE			_SC_PAGESIZE

Left out: Apple Libc. Hermit has no reliable page size and neither an api for it. See hermit-os/kernel#815.

lib/std/os.zig

lib/std/c/solaris.zig

sysconf() abstracts posix sysconf for comptime- and runtime probing. getDefaultPageSize() reads the Kernel provided default page size, which remains constant from program start to end. Reproduce added abi bits with: git clone --depth=1 https://github.com/DragonFlyBSD/DragonFlyBSD git clone --depth=1 https://git.FreeBSD.org/src.git freebsd git clone --depth=1 https://fuchsia.googlesource.com/fuchsia git clone --depth=1 https://github.com/haiku/haiku git clone --depth=1 https://github.com/Stichting-MINIX-Research-Foundation/minix/ git clone --depth=1 https://github.com/NetBSD/src netbsd git clone --depth=1 https://github.com/openbsd/src openbsd git clone --depth=1 https://github.com/kofemann/opensolaris git clone --depth=1 https://github.com/apple-open-source-mirror/Libc rg 'define.*_SC_PAGE_SIZE' -B 1 --vimgrep Closes ziglang#11308.

andrewrk

Thank you for working on this. A few requests-

andrewrk · 2023-09-18T07:59:58Z

lib/std/c/darwin.zig

@@ -233,6 +233,9 @@ pub const mach_header_64 = macho.mach_header_64;
 pub const mach_header = macho.mach_header;

 pub const _errno = __error;
+pub const _SC = struct {


No underscore, please.

andrewrk · 2023-09-18T08:02:56Z

lib/std/os.zig

+/// Returns page size assigned by the Kernel to the process. This size is
+/// constant during process lifetime, but other page sizes might be usable.
+pub fn getDefaultPageSize() error{UnknownPageSize}!usize {


This function does not belong in std.os (reminder: #5019)

I think it should go into std.heap.pageSize.

andrewrk · 2023-09-18T08:07:03Z

lib/std/os.zig

+            }
+            return sbi.PageSize;
+        },
+        // zig fmt: off


no need to turn off formatting

andrewrk · 2023-09-18T08:07:34Z

lib/std/os/test.zig

@@ -1,4 +1,4 @@
-const std = @import("../std.zig");
+const std = @import("std");


this can be left alone

andrewrk · 2023-09-18T08:08:10Z

lib/std/os/test.zig

+test "getDefaultPageSize smoke test" {
+    const page_size = try os.getDefaultPageSize();
+    switch (page_size) {
+        // zig fmt: off


please do not turn off code formatting

daurnimator reviewed Aug 1, 2023

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matu3ba force-pushed the learn_page_size branch 2 times, most recently from 8c57e1c to 99fbe13 Compare August 2, 2023 21:28

matu3ba changed the title ~~std.os: add getPageSize() with smoke tests~~ std.os: add getDefaultPageSize() with smoke tests Aug 2, 2023

matu3ba force-pushed the learn_page_size branch from 99fbe13 to 9e3f451 Compare August 2, 2023 21:31

matu3ba marked this pull request as ready for review August 2, 2023 21:32

matu3ba marked this pull request as draft August 2, 2023 22:36

matu3ba force-pushed the learn_page_size branch from cbe9203 to 8b4888b Compare August 6, 2023 16:29

matu3ba force-pushed the learn_page_size branch from 451182c to 8e01635 Compare August 13, 2023 22:36

matu3ba force-pushed the learn_page_size branch from 8e01635 to 1d9095a Compare August 20, 2023 23:51

matu3ba changed the title ~~std.os: add getDefaultPageSize() with smoke tests~~ std.os: add sysconf(), getDefaultPageSize() with smoke tests Aug 20, 2023

matu3ba force-pushed the learn_page_size branch 2 times, most recently from 9881625 to 7eabb78 Compare August 21, 2023 18:43

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Jan Philipp Hafer added 3 commits August 23, 2023 01:38

const choice -> var choice

587d3bd

expect wasm32 to have 64KB page size

5f11466

matu3ba force-pushed the learn_page_size branch from 8d9c341 to 5f11466 Compare August 22, 2023 23:38

matu3ba marked this pull request as ready for review August 23, 2023 00:29

andrewrk requested changes Sep 18, 2023

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std.os: add sysconf(), getDefaultPageSize() with smoke tests #16638

std.os: add sysconf(), getDefaultPageSize() with smoke tests #16638

matu3ba commented Jul 31, 2023 •

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andrewrk Sep 18, 2023

		@@ -1,4 +1,4 @@
		const std = @import("../std.zig");
		const std = @import("std");

std.os: add sysconf(), getDefaultPageSize() with smoke tests #16638

std.os: add sysconf(), getDefaultPageSize() with smoke tests #16638

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matu3ba commented Jul 31, 2023 •

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