From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tony Luck <tony.luck@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: get_vmalloc_info() and /proc/meminfo insanely expensive
Date: Thu, 13 Aug 2015 15:56:07 -0700 [thread overview]
Message-ID: <CA+55aFzh--4diDL5GutA_B7vGhjx03KLnYMWLc4KZPo_UqAwOA@mail.gmail.com> (raw)
In-Reply-To: <CA+8MBb+LGW0tc8Deta0qiJ0_N37LC2XxWSiHDYaQczYSE097vg@mail.gmail.com>
On Thu, Aug 13, 2015 at 2:15 PM, Tony Luck <tony.luck@gmail.com> wrote:
>
> could you at least care enough to write that as
>
> if (time_after(now, last + HZ)) {
Absolutely not. That would be wrong.
"time_after()" covers half the "unsigned long" space (very much on
purpose). We want the cached case to trigger _only_ for the much
tighter case of exactly 1000 jiffies.
Linus
next prev parent reply other threads:[~2015-08-13 22:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-13 3:29 get_vmalloc_info() and /proc/meminfo insanely expensive Linus Torvalds
2015-08-13 4:00 ` Andrew Morton
2015-08-13 5:52 ` Linus Torvalds
2015-08-13 7:42 ` Rasmus Villemoes
2015-08-13 16:50 ` Linus Torvalds
2015-08-13 18:32 ` Linus Torvalds
2015-08-13 18:52 ` Linus Torvalds
2015-08-13 19:50 ` David Rientjes
2015-08-13 20:04 ` Linus Torvalds
2015-08-13 21:15 ` Tony Luck
2015-08-13 22:56 ` Linus Torvalds [this message]
2015-08-13 20:26 ` Andrew Morton
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