From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [RFC]degradation on IPF due to hypercall set irq Date: Fri, 24 Nov 2006 09:46:47 +0000 Message-ID: References: <51CFAB8CB6883745AE7B93B3E084EBE207DD59@pdsmsx412.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51CFAB8CB6883745AE7B93B3E084EBE207DD59@pdsmsx412.ccr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Xu, Anthony" , Keir Fraser Cc: xen-devel@lists.xensource.com, xen-ia64-devel List-Id: xen-devel@lists.xenproject.org On 24/11/06 07:08, "Xu, Anthony" wrote: > This patch is for comments, and it is based on IPF, it may not apply to IA32 > side. > > This patch delivers interrupt and IO finish in the same hypercall > xc_hvm_set_irq_and_wakeup_cpu, > This eliminate all unnecessary hypercalls. > In the meantime, I add a mechanism for IDE DMA thread to wakeup qemu main > block(select) to > Deliver IDE DMA interrupt. Firstly, this patch is not against unstable tip. Secondly, we should make multicalls work rather than kludge a set_irq_and_notify_io_done type of hypercall. Applications are free to include any of the Xen public headers. We really just need a xc_multicall() API function. Thirdly, either we should keep the independent IDE-DMA thread or it should be entirely incorporated into the main qemu thread. Are pipe writes much faster than just doing a hypercall? If much slower, why is that? Could you work out a way of generically making IPC hypercalls faster (particularly from privileged user space -- could you trap straight to the hypervisor from user space rather than bouncing through guest kernel?). -- Keir