linux-kernel - Re: [PATCH v4 00/30] NT synchronization primitive driver

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Message-ID: <20240417052437.GJ30852@noisy.programming.kicks-ass.net>
Date: Wed, 17 Apr 2024 07:24:37 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Elizabeth Figura <zfigura@...eweavers.com>
Cc: Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	wine-devel@...ehq.org,
	André Almeida <andrealmeid@...lia.com>,
	Wolfram Sang <wsa@...nel.org>,
	Arkadiusz Hiler <ahiler@...eweavers.com>,
	Andy Lutomirski <luto@...nel.org>, linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Randy Dunlap <rdunlap@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>
Subject: Re: [PATCH v4 00/30] NT synchronization primitive driver

On Tue, Apr 16, 2024 at 04:18:24PM -0500, Elizabeth Figura wrote:

> Is the concern about poor performance when ntsync is in use, or is nesting a 
> lot of spinlocks like that something that could cause problems for unrelated 
> tasks? I'm not familiar enough with the scheduler to know if this can be 
> abused.

The problem is keeping preemption disabled for potentially a fairly long
time. By doing that you potentially affect the performance of other tasks.