From: Daniel Borkmann <dborkman@redhat.com>
To: George Spelvin <linux@horizon.com>
Cc: davem@davemloft.net, hannes@stressinduktion.org,
linux-kernel@vger.kernel.org, shemminger@osdl.org, tytso@mit.edu
Subject: Re: [PATCH 6/7] lib/random32.c: Randomize timeout to the millisecond, not the second
Date: Sun, 08 Jun 2014 14:28:13 +0200 [thread overview]
Message-ID: <539456DD.4020601@redhat.com> (raw)
In-Reply-To: <20140608113000.5423.qmail@ns.horizon.com>
On 06/08/2014 01:30 PM, George Spelvin wrote:
>> Fine by me this cleanup, although not strictly needed.
>
> Agreed. The timer slack is set to HZ (1 second) anyway.
>
> It just dawned on me that a simpler and more efficient way to do this
> (which I'll do in v2 of this) would be:
Note, when you talk about efficiency here, this is called once every
40+ secs ... ;)
> /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
> - expires = 40 + (prandom_u32() % 40);
> - seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
> + expires = 40*HZ + prandom_u32_max(40*HZ);
> + seed_timer.expires = jiffies + expires;
>
> That avoids calling msecs_to_jiffies entirely.
>
next prev parent reply other threads:[~2014-06-08 12:28 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-07 8:18 [PATCH 0/7] random32: Various minor cleanups George Spelvin
2014-06-07 8:19 ` [PATCH 1/7] lib/random32.c: Mark self-test data as __initconst George Spelvin
2014-06-08 12:06 ` Daniel Borkmann
2014-06-07 8:20 ` [PATCH 2/7] lib/random32.c: Remove excess calls to prandom_u32_state in initialization George Spelvin
2014-06-08 12:11 ` Daniel Borkmann
2014-06-08 12:19 ` George Spelvin
2014-06-07 8:22 ` [PATCH 3/7] lib/random32.c: Replace an #ifdef with a stub prandom_state_selftest() George Spelvin
2014-06-08 12:16 ` Daniel Borkmann
2014-06-08 12:27 ` George Spelvin
2014-06-07 8:25 ` [PATCH 4/7] lib/random32.c: Use <asm/unaligned.h> instead of hand-rolling it George Spelvin
2014-06-08 12:25 ` Daniel Borkmann
2014-06-08 12:40 ` George Spelvin
2014-06-08 20:26 ` Hannes Frederic Sowa
2014-06-10 15:13 ` Daniel Borkmann
2014-06-07 8:28 ` [PATCH 5/7] lib/random32.c: Make prandom_u32_max efficient for powers of 2 George Spelvin
2014-06-08 12:03 ` Daniel Borkmann
2014-06-08 17:34 ` Hannes Frederic Sowa
2014-06-08 20:02 ` Daniel Borkmann
2014-06-09 0:28 ` George Spelvin
2014-06-08 20:48 ` George Spelvin
2014-06-09 10:30 ` Hannes Frederic Sowa
2014-06-07 8:28 ` [PATCH 6/7] lib/random32.c: Randomize timeout to the millisecond, not the second George Spelvin
2014-06-08 10:43 ` Daniel Borkmann
2014-06-08 11:30 ` George Spelvin
2014-06-08 12:28 ` Daniel Borkmann [this message]
2014-06-08 12:42 ` George Spelvin
2014-06-08 20:01 ` Daniel Borkmann
2014-06-07 8:31 ` [PATCH 7/7] lib/random32.c: Remove redundant U suffixes on integers George Spelvin
2014-06-08 10:36 ` Daniel Borkmann
2014-06-08 11:14 ` George Spelvin
2014-06-08 12:05 ` Daniel Borkmann
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