 Home |
Products |
Support |
Community |
News |
xen-devel
Re: [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for bot
| To: | Jan Beulich <JBeulich@xxxxxxxxxx> |
|---|---|
| Subject: | Re: [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for both Xen 4.0.0 and Xen 4.0.1 to improve HVM scalability |
| From: | Keir Fraser <keir@xxxxxxx> |
| Date: | Tue, 16 Nov 2010 08:08:41 +0000 |
| Cc: | Song Xiang <classicxsong@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Haibo Chen <oldseawave@xxxxxxxxx> |
| Delivery-date: | Tue, 16 Nov 2010 00:09:39 -0800 |
| Dkim-signature: | v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:user-agent:date :subject:from:to:cc:message-id:thread-topic:thread-index:in-reply-to :mime-version:content-type:content-transfer-encoding; bh=Qsu5B3vGaAdZCLuyIYU+vecIywexGIiy+4Ubkf7MpOo=; b=bsMD4l+NRykkoG/Gz7sG2+RlaOCDY29P6ZcC2ebZEJfMojo+w9k5IhEpmRFnpsBEHz OKLqLac4GseYSSv08Px8wZwPi1lyaCrUe46yQ0ZBm5Hn+GD7UUcHt069AA6NC2uj7S1/ YXgelYcfXJ6YjsgDFLKkXs+BlcTQw4WXBJmAs= |
| Domainkey-signature: | a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:user-agent:date:subject:from:to:cc:message-id:thread-topic :thread-index:in-reply-to:mime-version:content-type :content-transfer-encoding; b=DbV71Qx/dP0CqXDjpuSBdNF12b+lxBnmv3k06xdBc1YNX+En/+miqdcMZNgIlRdew0 ZALrXAUu3/vnWa596DfVgYlaPChJzPEtB0FiLQnhHt7FFyaMzQvnLEScGZwrz3ZvmMi6 5/YkC6+pEiV7TlmuBcrF37msw/h4UUqpe/E4k= |
| Envelope-to: | www-data@xxxxxxxxxxxxxxxxxxx |
| In-reply-to: | <4CE246DB0200007800022704@xxxxxxxxxxxxxxxxxx> |
| List-help: | <mailto:xen-devel-request@lists.xensource.com?subject=help> |
| List-id: | Xen developer discussion <xen-devel.lists.xensource.com> |
| List-post: | <mailto:xen-devel@lists.xensource.com> |
| List-subscribe: | <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
| List-unsubscribe: | <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
| Sender: | xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
| Thread-index: | AcuFZXrh6cVYqk0ImkidVL+FZENROA== |
| Thread-topic: | [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for both Xen 4.0.0 and Xen 4.0.1 to improve HVM scalability |
| User-agent: | Microsoft-Entourage/12.27.0.100910 |
On 16/11/2010 07:54, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote: >> No need for your new field at all! It initially seems weird that this >> performs much better than the original code, but I guess it might: if all >> VCPUs are piling in here at the same time, rather than having to execute one >> by one, we'll have one go first and then the others will all execute >> simultaneously read-only in convoy... > > They'd need to re-measure whether this still provides a meaningful > benefit, I think. Definitely. I explicitly asked for that. Oh, also the approach is currently buggy. Although s->pm.tmr_val is atomic to read, it is not atomically updated in pmt_update_time(). Need to calculate new value for tmr_val in a local variable then update the shared field with an atomic_set()-alike *(volatile u32 *)&s->pm.tmr_val = x type of arrangement. For all this extra fragility, the perf win needs to be compelling. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
| Previous by Date: | Re: [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for both Xen 4.0.0 and Xen 4.0.1 to improve HVM scalability, Jan Beulich |
|---|---|
| Next by Date: | [Xen-devel] Re: blktap: Sync with XCP, dropping zero-copy., Daniel Stodden |
| Previous by Thread: | Re: [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for both Xen 4.0.0 and Xen 4.0.1 to improve HVM scalability, Jan Beulich |
| Next by Thread: | [SPAM] Re: [Xen-devel] A patch to xen/arch/x86/hvm/pmtimer.c for both Xen 4.0.0 and Xen 4.0.1 to improve HVM scalability, Jan Beulich |
| Indexes: | [Date] [Thread] [Top] [All Lists] |
