From: Ian Campbell <Ian.Campbell@citrix.com>
To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: wei.liu2@citrix.com, stefano.stabellini@eu.citrix.com,
Andrew Cooper <andrew.cooper3@citrix.com>,
xen-devel@lists.xen.org, JBeulich@suse.com,
Chao Peng <chao.p.peng@linux.intel.com>,
keir@xen.org
Subject: Re: [PATCH v2 2/5] tools: add routine to get CMT L3 event mask
Date: Wed, 7 Jan 2015 17:04:38 +0000 [thread overview]
Message-ID: <1420650278.18631.129.camel@citrix.com> (raw)
In-Reply-To: <21677.24788.869267.896079@mariner.uk.xensource.com>
On Wed, 2015-01-07 at 16:37 +0000, Ian Jackson wrote:
> > As the result of the hypercall is going to be the same, the
> > worse that a race could achieve is a wasted hypercall.
>
> This kind of analysis is unfounded in the presence of modern compilers
> with aggressive optimisations. At the very least, if you're going to
> do some caching like this, it needs a lock around it.
Even for a hypercall which is just "return 42" (at least between boots)?
Ian.
next prev parent reply other threads:[~2015-01-07 17:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-07 11:12 [PATCH v2 0/5] enable Memory Bandwidth Monitoring (MBM) for VMs Chao Peng
2015-01-07 11:12 ` [PATCH v2 1/5] x86: expose CMT L3 event mask to user space Chao Peng
2015-01-07 11:12 ` [PATCH v2 2/5] tools: add routine to get CMT L3 event mask Chao Peng
2015-01-07 11:27 ` Andrew Cooper
2015-01-07 16:37 ` Ian Jackson
2015-01-07 16:54 ` Wei Liu
2015-01-07 17:04 ` Ian Campbell [this message]
2015-01-07 17:09 ` Andrew Cooper
2015-01-07 21:43 ` Ian Jackson
2015-01-08 3:19 ` Chao Peng
2015-01-07 11:12 ` [PATCH v2 3/5] tools: correct coding style for psr Chao Peng
2015-01-07 11:16 ` Wei Liu
2015-01-07 11:12 ` [PATCH v2 4/5] tools: code refactoring for MBM Chao Peng
2015-01-07 12:15 ` Wei Liu
2015-01-07 11:12 ` [PATCH v2 5/5] tools: add total/local memory bandwith monitoring Chao Peng
2015-01-07 12:23 ` Wei Liu
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