From: Peter Zijlstra <peterz@infradead.org>
To: David Laight <david.laight.linux@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, u.kleine-koenig@baylibre.com,
Nicolas Pitre <npitre@baylibre.com>,
Oleg Nesterov <oleg@redhat.com>,
Biju Das <biju.das.jz@bp.renesas.com>
Subject: Re: [PATCH v3 next 00/10] Implement mul_u64_u64_div_u64_roundup()
Date: Sat, 14 Jun 2025 12:27:17 +0200 [thread overview]
Message-ID: <20250614102717.GK2278213@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250614095346.69130-1-david.laight.linux@gmail.com>
On Sat, Jun 14, 2025 at 10:53:36AM +0100, David Laight wrote:
> The pwm-stm32.c code wants a 'rounding up' version of mul_u64_u64_div_u64().
> This can be done simply by adding 'divisor - 1' to the 128bit product.
> Implement mul_u64_add_u64_div_u64(a, b, c, d) = (a * b + c)/d based on the
> existing code.
> Define mul_u64_u64_div_u64(a, b, d) as mul_u64_add_u64_div_u64(a, b, 0, d) and
> mul_u64_u64_div_u64_roundup(a, b, d) as mul_u64_add_u64_div_u64(a, b, d-1, d).
Another way to achieve the same would to to expose the remainder of
mul_u64_64_div_u64(), no?
next prev parent reply other threads:[~2025-06-14 10:27 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-14 9:53 David Laight
2025-06-14 9:53 ` [PATCH v3 next 01/10] lib: mul_u64_u64_div_u64() rename parameter 'c' to 'd' David Laight
2025-06-14 9:53 ` [PATCH v3 next 02/10] lib: mul_u64_u64_div_u64() Use WARN_ONCE() for divide errors David Laight
2025-06-14 15:17 ` Nicolas Pitre
2025-06-14 21:26 ` David Laight
2025-06-14 22:23 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 03/10] lib: mul_u64_u64_div_u64() simplify check for a 64bit product David Laight
2025-06-14 14:01 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 04/10] lib: Add mul_u64_add_u64_div_u64() and mul_u64_u64_div_u64_roundup() David Laight
2025-06-14 14:06 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 05/10] lib: Add tests for mul_u64_u64_div_u64_roundup() David Laight
2025-06-14 15:19 ` Nicolas Pitre
2025-06-17 4:30 ` Nicolas Pitre
2025-09-18 14:00 ` Uwe Kleine-König
2025-09-18 21:06 ` David Laight
2025-06-14 9:53 ` [PATCH v3 next 06/10] lib: test_mul_u64_u64_div_u64: Test both generic and arch versions David Laight
2025-06-14 15:25 ` Nicolas Pitre
2025-06-18 1:39 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 07/10] lib: mul_u64_u64_div_u64() optimise multiply on 32bit x86 David Laight
2025-06-14 15:31 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 08/10] lib: mul_u64_u64_div_u64() Separate multiply to a helper for clarity David Laight
2025-06-14 15:37 ` Nicolas Pitre
2025-06-14 21:30 ` David Laight
2025-06-14 22:27 ` Nicolas Pitre
2025-06-14 9:53 ` [PATCH v3 next 09/10] lib: mul_u64_u64_div_u64() Optimise the divide code David Laight
2025-06-17 4:16 ` Nicolas Pitre
2025-06-18 1:33 ` Nicolas Pitre
2025-06-18 9:16 ` David Laight
2025-06-18 15:39 ` Nicolas Pitre
2025-06-18 16:42 ` Nicolas Pitre
2025-06-18 17:54 ` David Laight
2025-06-18 20:12 ` Nicolas Pitre
2025-06-18 22:26 ` David Laight
2025-06-19 2:43 ` Nicolas Pitre
2025-06-19 8:32 ` David Laight
2025-06-26 21:46 ` David Laight
2025-06-27 3:48 ` Nicolas Pitre
2025-07-09 14:24 ` David Laight
2025-07-10 9:39 ` 答复: [????] " Li,Rongqing
2025-07-10 10:35 ` David Laight
2025-07-11 21:17 ` David Laight
2025-07-11 21:40 ` Nicolas Pitre
2025-07-14 7:06 ` David Laight
2025-06-14 9:53 ` [PATCH v3 next 10/10] lib: test_mul_u64_u64_div_u64: Test the 32bit code on 64bit David Laight
2025-06-14 10:27 ` Peter Zijlstra [this message]
2025-06-14 11:59 ` [PATCH v3 next 00/10] Implement mul_u64_u64_div_u64_roundup() David Laight
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