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From: Andrew Jones <ajones@ventanamicro.com>
To: Samuel Holland <samuel.holland@sifive.com>
Cc: Conor Dooley <conor@kernel.org>,
	Juhan Jin <juhan.jin@foxmail.com>,
	 linux-riscv@lists.infradead.org, peterz@infradead.org,
	jpoimboe@kernel.org, juhanj2@illinois.edu,
	 alexghiti@rivosinc.com, palmer@dabbelt.com
Subject: Re: Is RISC-V Static Call worth implementing ?
Date: Sat, 14 Sep 2024 15:34:07 +0200	[thread overview]
Message-ID: <20240914-2996cb645bae4145c0619c58@orel> (raw)
In-Reply-To: <54ce36a6-8be1-4ce8-b246-2255df333d00@sifive.com>

On Fri, Sep 13, 2024 at 06:50:37PM GMT, Samuel Holland wrote:
> On 2024-09-13 3:55 PM, Conor Dooley wrote:
> > On Fri, Sep 13, 2024 at 03:05:33AM -0500, Juhan Jin wrote:
> >> Hi folks,
> >>
> >> I’m interested in implementing Static Call for RISC-V, and I want to
> >> know whether it is worth the efforts to implement Static Call for
> >> RISC-V.
> >>
> >> Does the aforementioned benefits merit a RISC-V static call implementation 
> >> (especially inline)? Or are the benefits so negligible that it’s simply not 
> >> worth the effort to do a RISC-V implementation?
> > 
> > Pretty sure we've talked about wanting it before - Samuel, Alex, Drew
> > Jones or Palmer might remember best what exactly we wanted it for
> > however, as I do not.
> 
> If I remember correctly, we had discussed it in the context of non-coherent DMA
> operations, but we decided that the benefit was negligible for that use case.
> 
> There are other places that could likely benefit from static calls, such as
> Sv39/Sv48/Sv57 differences, some users of riscv_has_extension_*(), or maybe some
> hot indirect SBI functions like sbi_set_timer(). But it depends on the overhead.

When guests have steal time accounting enabled then update_rq_clock()
would also likely benefit.

Thanks,
drew

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  reply	other threads:[~2024-09-14 13:34 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-13  8:05 Is RISC-V Static Call worth implementing ? Juhan Jin
2024-09-13 20:55 ` Conor Dooley
2024-09-13 23:50   ` Samuel Holland
2024-09-14 13:34     ` Andrew Jones [this message]
2024-09-13 22:42 ` Charlie Jenkins

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