From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: x86@kernel.org, kvm@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
gleb@redhat.com, Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC dontapply 5/5] kvm_para: guest side for eoi avoidance
Date: Tue, 08 May 2012 17:26:55 +0200 [thread overview]
Message-ID: <4FA93B3F.3000906@redhat.com> (raw)
In-Reply-To: <5e1399d9e743668a87f31d8f2b83cad862c60728.1334833141.git.mst@redhat.com>
Il 23/04/2012 16:04, Michael S. Tsirkin ha scritto:
> +/* Our own copy of __test_and_clear_bit to make sure
> + * it is done with a single instruction */
Is this for microoptimization or correctness? If the latter, it does
not ensure anything without a "lock" prefix.
Paolo
> +static inline int kvm_test_and_clear_bit(int nr, volatile u16* addr)
> +{
> + int oldbit;
> +
> + asm volatile("btr %2,%1\n\t"
> + "sbb %0,%0"
> + : "=r" (oldbit), BITOP_ADDR_CONSTRAINT(*addr) : "Ir" (nr));
> + return oldbit;
next prev parent reply other threads:[~2012-05-08 15:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-23 14:03 [PATCH RFC 0/5] apic: eoi optimization support Michael S. Tsirkin
2012-04-23 14:04 ` [PATCH RFC 1/5] apic: fix typo EIO_ACK -> EOI_ACK and document Michael S. Tsirkin
2012-04-23 14:04 ` [PATCH RFC 2/5] apic: use symbolic APIC_EOI_ACK Michael S. Tsirkin
2012-04-23 14:04 ` [PATCH RFC 3/5] x86: add apic->eoi_write callback Michael S. Tsirkin
2012-04-23 14:04 ` [PATCH RFC 4/5] x86: eoi micro-optimization Michael S. Tsirkin
2012-04-23 14:04 ` [PATCH RFC dontapply 5/5] kvm_para: guest side for eoi avoidance Michael S. Tsirkin
2012-04-24 6:50 ` Gleb Natapov
2012-04-24 6:58 ` Michael S. Tsirkin
2012-04-24 7:07 ` Gleb Natapov
2012-05-08 15:26 ` Paolo Bonzini [this message]
2012-05-08 15:28 ` Gleb Natapov
2012-05-08 15:45 ` H. Peter Anvin
2012-05-08 16:32 ` Gleb Natapov
2012-05-08 16:57 ` Michael S. Tsirkin
2012-05-08 18:06 ` H. Peter Anvin
2012-05-08 19:36 ` Michael S. Tsirkin
2012-05-07 10:35 ` [PATCH RFC 0/5] apic: eoi optimization support Ingo Molnar
2012-05-07 10:59 ` Michael S. Tsirkin
2012-05-07 11:40 ` Ingo Molnar
2012-05-07 11:47 ` Avi Kivity
2012-05-07 11:57 ` Ingo Molnar
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