From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Sparse Mailing-list <linux-sparse@vger.kernel.org>
Subject: Re: [PATCH 00/11] pragma once: treewide conversion
Date: Mon, 1 Mar 2021 01:29:52 +0100 [thread overview]
Message-ID: <20210301002952.hdn5fngwfeo5nhce@mail> (raw)
In-Reply-To: <YDvwVlG/fqVxVYlQ@localhost.localdomain>
On Sun, Feb 28, 2021 at 10:34:46PM +0300, Alexey Dobriyan wrote:
>
> gcc does
>
> open "/" + "whatever between quotes"
> fstat
>
> so that "1.h" and "./1.h" differ
When I try the following with GCC 10.2:
$ cat header.h
#pragma once
#include "./header.h"
.. plenty of stuff ..
$ strace -f gcc -E header.h
I see that the file is opened 4 times (3 times with the name "header.h"
and once with "./header.h"). Each of these open is followed by a fstat().
More annoyingly, the file is also read 4 times (3 times entirely and once
only the fist 4096 bytes).
When the equivalent is done with an include guard instead, the file is
only read twice (once with each names) and read twice (entirely).
-- Luc
prev parent reply other threads:[~2021-03-01 0:30 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-28 16:57 [PATCH 00/11] pragma once: treewide conversion Alexey Dobriyan
2021-02-28 16:58 ` [PATCH 01/11] pragma once: delete include/linux/atm_suni.h Alexey Dobriyan
2021-02-28 19:05 ` Jakub Kicinski
2021-02-28 16:59 ` [PATCH 02/11] pragma once: convert arch/arm/tools/gen-mach-types Alexey Dobriyan
2021-03-01 10:19 ` Russell King - ARM Linux admin
2021-03-02 15:15 ` Alexey Dobriyan
2021-02-28 16:59 ` [PATCH 03/11] pragma once: convert arch/s390/tools/gen_facilities.c Alexey Dobriyan
2021-02-28 17:00 ` [PATCH 04/11] pragma once: convert drivers/gpu/drm/pl111/pl111_nomadik.h Alexey Dobriyan
2021-03-01 14:41 ` Linus Walleij
2021-02-28 17:01 ` [PATCH 05/11] pragma once: convert drivers/scsi/qla2xxx/qla_target.h Alexey Dobriyan
2021-02-28 22:07 ` Bart Van Assche
2021-02-28 17:02 ` [PATCH 06/11] pragma once: convert include/linux/cb710.h Alexey Dobriyan
2021-03-03 23:13 ` Michał Mirosław
2021-02-28 17:02 ` [PATCH 07/11] pragma once: convert kernel/time/timeconst.bc Alexey Dobriyan
2021-02-28 17:03 ` [PATCH 08/11] pragma once: convert scripts/atomic/ Alexey Dobriyan
2021-03-01 7:55 ` Peter Zijlstra
2021-02-28 17:04 ` [PATCH 09/11] pragma once: convert scripts/selinux/genheaders/genheaders.c Alexey Dobriyan
2021-02-28 18:37 ` Paul Moore
2021-02-28 18:57 ` Alexey Dobriyan
2021-02-28 17:05 ` [PATCH 10/11] pragma once: delete few backslashes Alexey Dobriyan
2021-03-01 8:54 ` Ido Schimmel
2021-03-02 19:00 ` Vineet Gupta
2021-03-04 14:22 ` Edward Cree
2021-03-23 10:09 ` Pavel Machek
2021-02-28 17:05 ` [PATCH 11/11] pragma once: conversion script (in Python 2) Alexey Dobriyan
2021-02-28 17:11 ` [PATCH 12/11] pragma once: scripted treewide conversion Alexey Dobriyan
2021-03-01 17:35 ` Darrick J. Wong
2021-02-28 17:46 ` [PATCH 00/11] pragma once: " Linus Torvalds
2021-02-28 19:34 ` Alexey Dobriyan
2021-02-28 20:00 ` Linus Torvalds
[not found] ` <877dmo10m3.fsf@tromey.com>
2021-03-03 20:17 ` Linus Torvalds
2021-03-04 13:55 ` David Laight
2021-03-04 20:16 ` Linus Torvalds
2021-03-05 9:19 ` David Laight
2021-03-05 21:23 ` Linus Torvalds
2021-03-06 13:07 ` Miguel Ojeda
2021-03-06 21:33 ` Linus Torvalds
2021-03-23 10:03 ` Pavel Machek
2021-03-01 0:29 ` Luc Van Oostenryck [this message]
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