From: David Laight <david.laight.linux@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, u.kleine-koenig@baylibre.com,
Nicolas Pitre <npitre@baylibre.com>,
Peter Zijlstra <peterz@infradead.org>,
Biju Das <biju.das.jz@bp.renesas.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Li RongQing <lirongqing@baidu.com>, Yu Kuai <yukuai3@huawei.com>,
Khazhismel Kumykov <khazhy@chromium.org>,
Jens Axboe <axboe@kernel.dk>,
x86@kernel.org
Subject: Re: [PATCH v4 next 0/9] Implement mul_u64_u64_div_u64_roundup()
Date: Fri, 31 Oct 2025 16:17:08 +0000 [thread overview]
Message-ID: <20251031161708.312343f8@pumpkin> (raw)
In-Reply-To: <20251031135255.GA22251@redhat.com>
On Fri, 31 Oct 2025 14:52:56 +0100
Oleg Nesterov <oleg@redhat.com> wrote:
> On 10/29, 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).
>
> Sorry for the noise. Can't review due to the lack of knowledge.
> But this reminds me... What about
>
> [PATCH v3 1/2] x86/math64: handle #DE in mul_u64_u64_div_u64()
> https://lore.kernel.org/all/20250815164055.GA13444@redhat.com
>
> ?
>
> should I resend it once again or we don't care?
I'd remembered that as well.
I'll do a new version of that on top as a separate patch.
Probably when this set has been merged further.
David
prev parent reply other threads:[~2025-10-31 16:17 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-29 17:38 [PATCH v4 next 0/9] Implement mul_u64_u64_div_u64_roundup() David Laight
2025-10-29 17:38 ` [PATCH v4 next 1/9] lib: mul_u64_u64_div_u64() rename parameter 'c' to 'd' David Laight
2025-10-29 17:38 ` [PATCH v4 next 2/9] lib: mul_u64_u64_div_u64() Combine overflow and divide by zero checks David Laight
2025-10-29 18:02 ` Nicolas Pitre
2025-10-29 17:38 ` [PATCH v4 next 3/9] lib: mul_u64_u64_div_u64() simplify check for a 64bit product David Laight
2025-10-29 18:11 ` Nicolas Pitre
2025-10-31 9:19 ` David Laight
2025-10-31 17:26 ` Nicolas Pitre
2025-10-31 18:04 ` David Laight
2025-10-31 18:45 ` Nicolas Pitre
2025-10-31 20:12 ` David Laight
2025-10-29 17:38 ` [PATCH v4 next 4/9] lib: Add mul_u64_add_u64_div_u64() and mul_u64_u64_div_u64_roundup() David Laight
2025-10-29 18:17 ` Nicolas Pitre
2025-10-31 20:59 ` David Laight
2025-11-01 2:12 ` Andrew Morton
2025-10-29 17:38 ` [PATCH v4 next 5/9] lib: Add tests for mul_u64_u64_div_u64_roundup() David Laight
2025-10-29 18:26 ` Nicolas Pitre
2025-10-29 17:38 ` [PATCH v4 next 6/9] lib: test_mul_u64_u64_div_u64: Test both generic and arch versions David Laight
2025-10-29 18:53 ` Nicolas Pitre
2025-11-01 19:35 ` kernel test robot
2025-11-01 20:59 ` kernel test robot
2025-11-02 10:36 ` David Laight
2025-10-29 17:38 ` [PATCH v4 next 7/9] lib: mul_u64_u64_div_u64() optimise multiply on 32bit x86 David Laight
2025-10-29 19:01 ` Nicolas Pitre
2025-10-29 17:38 ` [PATCH v4 next 8/9] lib: mul_u64_u64_div_u64() Optimise the divide code David Laight
2025-10-29 20:47 ` Nicolas Pitre
2025-10-29 17:38 ` [PATCH v4 next 9/9] lib: test_mul_u64_u64_div_u64: Test the 32bit code on 64bit David Laight
2025-10-29 20:48 ` Nicolas Pitre
2025-10-31 4:29 ` [PATCH v4 next 0/9] Implement mul_u64_u64_div_u64_roundup() Andrew Morton
2025-11-04 17:16 ` Nicolas Pitre
2025-10-31 13:52 ` Oleg Nesterov
2025-10-31 16:17 ` David Laight [this message]
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