From mboxrd@z Thu Jan  1 00:00:00 1970
From: Haitao Shan <maillists.shan@gmail.com>
Subject: Re: Xen 4.1 rc1 test report
Date: Tue, 25 Jan 2011 14:24:29 +0800
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To: "Zheng, Shaohui" <shaohui.zheng@intel.com>, Keir Fraser <keir@xen.org>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
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> Performance(1 bug)
> 1. guest boot very slowly without limit dom0 cpu number on EX (Intel)
> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1719
>

This bug happened 1 year before. Keir has made a fix with c/s 20841,
which essentially holds the locked (and hence allocated) hypercall
page so that next hypercall can reuse it without doing alloc and mlock
again. By doing this, overhead of rschedule IPI as a result of
frequent mlock is greatly reduced.

Late in year 2010, libxc introduced a new mechanism called hypercall
buffers, as you can refer c/s 22288~22312. Keir's fix is dropped in
this new framework. As a result, the bug appears again.
Probably the new framework auther can pick up Keir's fix again?

Shan Haitao