From: Peter Zijlstra <peterz@infradead.org>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
Aabid Rushdi <Aabid.Rushdi@synopsys.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-perf-users@vger.kernel.org"
<linux-perf-users@vger.kernel.org>,
"dvhart@linux.intel.com" <dvhart@linux.intel.com>,
"dsahern@gmail.com" <dsahern@gmail.com>,
"acme@redhat.com" <acme@redhat.com>
Subject: Re: [RFC] perf: fix building for ARCv1
Date: Mon, 19 Oct 2015 11:51:57 +0200 [thread overview]
Message-ID: <20151019095157.GM3816@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <C2D7FE5348E1B147BCA15975FBA23075F44CB023@IN01WEMBXA.internal.synopsys.com>
On Mon, Oct 19, 2015 at 09:46:35AM +0000, Vineet Gupta wrote:
> On ARC we could use the atomic EXchange to implement a user space only binary
> semaphore - these atomic ops will be small duration so it is OK to spin wait for a
> little bit. That's how the old pthread library worked for ARC w/o any atomic support.
That has the obvious problem of lock-holder-preemption and the horrible
performance issues that result from that.
I think the syscall at least has deterministic behaviour, whereas that
userspace spin loop has this abysmal worst case thing.
next prev parent reply other threads:[~2015-10-19 9:52 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1445088959-3058-1-git-send-email-abrodkin@synopsys.com>
2015-10-17 14:19 ` [RFC] perf: fix building for ARCv1 Vineet Gupta
2015-10-18 11:15 ` Alexey Brodkin
2015-10-18 23:14 ` Andi Kleen
2015-10-19 4:58 ` Vineet Gupta
2015-10-19 5:49 ` Andi Kleen
2015-10-19 9:28 ` Vineet Gupta
2015-10-19 9:35 ` Peter Zijlstra
2015-10-19 9:46 ` Vineet Gupta
2015-10-19 9:51 ` Peter Zijlstra [this message]
2015-10-19 10:04 ` Vineet Gupta
2015-10-20 8:00 ` Vineet Gupta
2015-10-20 10:11 ` Peter Zijlstra
2015-10-20 10:45 ` Vineet Gupta
2015-10-29 15:58 ` Alexey Brodkin
2015-10-30 6:19 ` Vineet Gupta
2016-02-03 16:20 ` Alexey Brodkin
[not found] ` <1454516455.2811.4.camel__10775.5710989752$1454516490$gmane$org@synopsys.com>
2016-02-04 4:13 ` Vineet Gupta
2016-02-05 11:18 ` Noam Camus
[not found] ` <20160205161027.GG28242@kernel.org>
2016-02-10 3:09 ` Vineet Gupta
2016-10-18 18:58 ` Vineet Gupta
2016-10-24 16:17 ` [PATCH-v2] ARC: syscall for userspace cmpxchg assist Vineet Gupta
2016-11-04 20:16 ` Vineet Gupta
2016-11-07 18:50 ` [PATCH] ARC: tweak semantics of " Vineet Gupta
2015-10-30 6:21 ` [RFC] perf: fix building for ARCv1 Vineet Gupta
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