From: Hollis Blanchard <hollisb@us.ibm.com>
To: carsteno@de.ibm.com
Cc: Avi Kivity <avi@qumranet.com>,
"Yang, Sheng" <sheng.yang@intel.com>,
kvm@vger.kernel.org,
Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
xiantao.zhang@intel.com, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 2/5] kvmtrace: make cycle calculation architecture aware
Date: Fri, 11 Jul 2008 15:19:54 +0000 [thread overview]
Message-ID: <1215789594.28760.7.camel@localhost.localdomain> (raw)
In-Reply-To: <48770CEF.6090102@de.ibm.com>
On Fri, 2008-07-11 at 09:34 +0200, Carsten Otte wrote:
> Avi Kivity wrote:
> > What is the overhead of ktime_get()?
> I think I'd like an arch specific timestamp. This way we could use our
> clock-cycle-granularity-non-privileged-timestamp instruction ;-). If
> we need a common implementation, I don't think there's much difference
> between different syscalls in terms of overhead.
Carsten tried to elaborate on IRC, but the summary is that a) time on
S390 is complicated, and b) they have a time source that yields finer
granularity than nanoseconds. So I'm inclined to say fine, we can have
an arch-specific hook, and almost every arch will just use
getnstimeofday().
--
Hollis Blanchard
IBM Linux Technology Center
WARNING: multiple messages have this Message-ID (diff)
From: Hollis Blanchard <hollisb@us.ibm.com>
To: carsteno@de.ibm.com
Cc: Avi Kivity <avi@qumranet.com>,
"Yang, Sheng" <sheng.yang@intel.com>,
kvm@vger.kernel.org,
Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
xiantao.zhang@intel.com, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 2/5] kvmtrace: make cycle calculation architecture aware
Date: Fri, 11 Jul 2008 10:19:54 -0500 [thread overview]
Message-ID: <1215789594.28760.7.camel@localhost.localdomain> (raw)
In-Reply-To: <48770CEF.6090102@de.ibm.com>
On Fri, 2008-07-11 at 09:34 +0200, Carsten Otte wrote:
> Avi Kivity wrote:
> > What is the overhead of ktime_get()?
> I think I'd like an arch specific timestamp. This way we could use our
> clock-cycle-granularity-non-privileged-timestamp instruction ;-). If
> we need a common implementation, I don't think there's much difference
> between different syscalls in terms of overhead.
Carsten tried to elaborate on IRC, but the summary is that a) time on
S390 is complicated, and b) they have a time source that yields finer
granularity than nanoseconds. So I'm inclined to say fine, we can have
an arch-specific hook, and almost every arch will just use
getnstimeofday().
--
Hollis Blanchard
IBM Linux Technology Center
next prev parent reply other threads:[~2008-07-11 15:19 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-07 13:56 [PATCH 0/5] kvmtrace: add powerpc support for KVM_TRACE ehrhardt
2008-07-07 13:56 ` ehrhardt
2008-07-07 13:56 ` [PATCH 1/5] kvmtrace: Remove use of bit fields in kvm trace structure v3 ehrhardt
2008-07-07 13:56 ` ehrhardt
2008-07-07 13:56 ` [PATCH 2/5] kvmtrace: make cycle calculation architecture aware ehrhardt
2008-07-07 13:56 ` ehrhardt
2008-07-07 15:45 ` Hollis Blanchard
2008-07-07 15:45 ` Hollis Blanchard
2008-07-09 8:25 ` Christian Ehrhardt
2008-07-09 8:25 ` Christian Ehrhardt
2008-07-07 16:37 ` Hollis Blanchard
2008-07-07 16:37 ` Hollis Blanchard
2008-07-09 9:17 ` Christian Ehrhardt
2008-07-09 9:17 ` Christian Ehrhardt
2008-07-09 15:03 ` Hollis Blanchard
2008-07-09 15:03 ` Hollis Blanchard
2008-07-10 10:22 ` Yang, Sheng
2008-07-10 10:22 ` Yang, Sheng
2008-07-10 10:24 ` Yang, Sheng
2008-07-10 10:24 ` Yang, Sheng
2008-07-10 13:32 ` Avi Kivity
2008-07-10 13:32 ` Avi Kivity
2008-07-11 1:06 ` Yang, Sheng
2008-07-11 1:06 ` Yang, Sheng
2008-07-11 7:34 ` Carsten Otte
2008-07-11 7:34 ` Carsten Otte
2008-07-11 15:19 ` Hollis Blanchard [this message]
2008-07-11 15:19 ` Hollis Blanchard
2008-07-13 15:41 ` Avi Kivity
2008-07-13 15:41 ` Avi Kivity
2008-07-14 7:44 ` Christian Borntraeger
2008-07-14 7:44 ` Christian Borntraeger
2008-07-07 13:56 ` [PATCH 3/5] kvmppc: kvmtrace: enable KVM_TRACE building for powerpc ehrhardt
2008-07-07 13:56 ` ehrhardt
2008-07-07 13:56 ` [PATCH 4/5] kvmppc: kvmtrace: adds trace points for ppc tlb activity v2 ehrhardt
2008-07-07 13:56 ` ehrhardt
2008-07-07 13:56 ` [PATCH 5/5] kvmppc: kvmtrace: trace powerpc instruction emulation ehrhardt
2008-07-07 13:56 ` ehrhardt
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