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From: anup@brainfault.org (Anup Patel)
To: linux-riscv@lists.infradead.org
Subject: [PATCH 1/4] irqchip: sifive-plic: Pre-compute context hart base and enable base
Date: Mon, 12 Nov 2018 09:57:02 +0530	[thread overview]
Message-ID: <CAAhSdy1dYGShvtUEdDARw_8viC5P5MdMLBQOhe56nu6TMNgGaA@mail.gmail.com> (raw)
In-Reply-To: <20181109084256.GA6508@infradead.org>

On Fri, Nov 9, 2018 at 2:12 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Oct 22, 2018 at 05:15:14PM +0530, Anup Patel wrote:
> > This patch does following optimizations:
> > 1. Pre-compute hart base for each context handler
> > 2. Pre-compute enable base for each context handler
>
> Why?

This is micro-optimizations. We don't need to re-compute
hart base and hart enable base everytime.

>
> > 3. Have enable lock for each context handler instead
> > of global plic_toggle_lock
>
> Why?  Also even if you want this it should be a separate patch.

Well, the PLIC register space it a bit strange.

Most PLIC context specific registers are in one place
except context IRQ enable registers which are part of
global registers.

To handle this, we had a global plic_toggle_lock which
was taken whenever PLIC driver touched context IRQ
enable registers. Instead of this, we can have per-context
IRQ enable lock for more granular locking.

Later when we implement IRQ set_affinity, we touch
IRQ enable registers of each context whenever IRQ
affinity changes. This fine grained IRQ enable locking
helps when IRQ load-balancer is changing affinity of
different IRQs parallely on separate cores. Again this
is a micro-optimization.

>
> >  #define PRIORITY_BASE                        0
> > -#define     PRIORITY_PER_ID          4
> > +#define PRIORITY_PER_ID                      4
>
> Also please drop the random whitespace changes.

Instead of dropping I will make it separate patch because
we are replacing "\t" between #define and define_name
with a space.

Regards,
Anup

WARNING: multiple messages have this Message-ID
From: Anup Patel <anup@brainfault.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
	Jason Cooper <jason@lakedaemon.net>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>, Atish Patra <atish.patra@wdc.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH 1/4] irqchip: sifive-plic: Pre-compute context hart base and enable base
Date: Mon, 12 Nov 2018 09:57:02 +0530	[thread overview]
Message-ID: <CAAhSdy1dYGShvtUEdDARw_8viC5P5MdMLBQOhe56nu6TMNgGaA@mail.gmail.com> (raw)
Message-ID: <20181112042702.Y6rZOcIKzl62AQPh9stJDb15C9lsHQhTxHAJ6SZ2Yjk@z> (raw)
In-Reply-To: <20181109084256.GA6508@infradead.org>

On Fri, Nov 9, 2018 at 2:12 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Oct 22, 2018 at 05:15:14PM +0530, Anup Patel wrote:
> > This patch does following optimizations:
> > 1. Pre-compute hart base for each context handler
> > 2. Pre-compute enable base for each context handler
>
> Why?

This is micro-optimizations. We don't need to re-compute
hart base and hart enable base everytime.

>
> > 3. Have enable lock for each context handler instead
> > of global plic_toggle_lock
>
> Why?  Also even if you want this it should be a separate patch.

Well, the PLIC register space it a bit strange.

Most PLIC context specific registers are in one place
except context IRQ enable registers which are part of
global registers.

To handle this, we had a global plic_toggle_lock which
was taken whenever PLIC driver touched context IRQ
enable registers. Instead of this, we can have per-context
IRQ enable lock for more granular locking.

Later when we implement IRQ set_affinity, we touch
IRQ enable registers of each context whenever IRQ
affinity changes. This fine grained IRQ enable locking
helps when IRQ load-balancer is changing affinity of
different IRQs parallely on separate cores. Again this
is a micro-optimization.

>
> >  #define PRIORITY_BASE                        0
> > -#define     PRIORITY_PER_ID          4
> > +#define PRIORITY_PER_ID                      4
>
> Also please drop the random whitespace changes.

Instead of dropping I will make it separate patch because
we are replacing "\t" between #define and define_name
with a space.

Regards,
Anup

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  parent reply	other threads:[~2018-11-12  4:27 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-22 11:45 [PATCH 0/4] IRQ affinity support in PLIC driver Anup Patel
2018-10-22 11:45 ` Anup Patel
2018-10-22 11:45 ` [PATCH 1/4] irqchip: sifive-plic: Pre-compute context hart base and enable base Anup Patel
2018-10-22 11:45   ` Anup Patel
2018-11-09  8:42   ` Christoph Hellwig
2018-11-09  8:42     ` Christoph Hellwig
2018-11-12  4:27     ` Anup Patel [this message]
2018-11-12  4:27       ` Anup Patel
2018-10-22 11:45 ` [PATCH 2/4] irqchip: sifive-plic: More flexible plic_irq_toggle() Anup Patel
2018-10-22 11:45   ` Anup Patel
2018-11-09  8:43   ` Christoph Hellwig
2018-11-09  8:43     ` Christoph Hellwig
2018-11-12 12:33     ` Anup Patel
2018-11-12 12:33       ` Anup Patel
2018-10-22 11:45 ` [PATCH 3/4] irqchip: sifive-plic: Differentiate between PLIC handler and context Anup Patel
2018-10-22 11:45   ` Anup Patel
2018-10-22 11:45 ` [PATCH 4/4] irqchip: sifive-plic: Implement irq_set_affinity() for SMP host Anup Patel
2018-10-22 11:45   ` Anup Patel

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