From: "hch@lst.de" <hch@lst.de>
To: Atish Patra <Atish.Patra@wdc.com>
Cc: "linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"palmer@sifive.com" <palmer@sifive.com>,
"hch@lst.de" <hch@lst.de>,
"paul.walmsley@sifive.com" <paul.walmsley@sifive.com>
Subject: Re: [PATCH 3/6] riscv: optimize send_ipi_single
Date: Mon, 26 Aug 2019 13:29:37 +0200 [thread overview]
Message-ID: <20190826112937.GB15002@lst.de> (raw)
In-Reply-To: <570f358ed76092a4072b5acedd4ddb34c318ff9b.camel@wdc.com>
On Sat, Aug 24, 2019 at 12:26:26AM +0000, Atish Patra wrote:
> > static void send_ipi_single(int cpu, enum ipi_message_type op)
> > {
> > - send_ipi_mask(cpumask_of(cpu), op);
> > + int hartid = cpuid_to_hartid_map(cpu);
> > +
> > + smp_mb__before_atomic();
> > + set_bit(op, &ipi_data[cpu].bits);
> > + smp_mb__after_atomic();
> > +
> > + sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
>
> The only cost save I see is you don't have to cpumask_clear anymore.
> Is there any other cost save ? If not is it worth duplicating the code
> ?
>
> May be I am being too pedantic here.. :) :)
It avoids the additional potentially huge cpumask, and generally makes
the code a lot more obvious. This might not really be needed, but
helps with sharing the code nicely with the native IPI path.
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next prev parent reply other threads:[~2019-08-26 11:29 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 14:58 misc riscv cleanups Christoph Hellwig
2019-08-21 14:58 ` [PATCH 1/6] riscv: refactor the IPI code Christoph Hellwig
2019-08-24 1:03 ` Atish Patra
2019-09-05 8:44 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 2/6] riscv: cleanup send_ipi_mask Christoph Hellwig
2019-08-24 0:11 ` Atish Patra
2019-08-26 11:28 ` hch
2019-08-27 18:45 ` Atish Patra
2019-09-05 8:46 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 3/6] riscv: optimize send_ipi_single Christoph Hellwig
2019-08-24 0:26 ` Atish Patra
2019-08-26 11:29 ` hch [this message]
2019-08-27 18:48 ` Atish Patra
2019-09-05 8:48 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 4/6] riscv: cleanup riscv_cpuid_to_hartid_mask Christoph Hellwig
2019-08-24 0:03 ` Atish Patra
2019-09-05 8:50 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 5/6] riscv: don't use the rdtime(h) pseudo-instructions Christoph Hellwig
2019-08-24 0:37 ` Atish Patra
2019-08-24 0:43 ` Atish Patra
2019-08-26 11:30 ` hch
2019-08-27 18:50 ` Atish Patra
2019-09-05 8:55 ` Paul Walmsley
2019-08-21 14:58 ` [PATCH 6/6] riscv: move the TLB flush logic out of line Christoph Hellwig
2019-08-24 0:03 ` Atish Patra
2019-09-05 8:58 ` Paul Walmsley
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