This will allow us to use OS specific interfaces to ensure that the
allocated memory is safe for use as a hypercall buffer in the future.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Constantly m(un)locking memory can have significant overhead on
systems with large numbers of CPUs. This was previously fixed by
20841:fbe8f32fa257 but this was dropped during the transition to
hypercall buffers.
Introduce a small cache of single page hypercall buffer allocations
which can be resused to avoid this overhead.
Add some statistics tracking to the hypercall buffer allocations.
The cache size of 4 was chosen based on these statistics since they
indicated that 2 pages was sufficient to satisfy all concurrent single
page hypercall buffer allocations seen during "xl create", "xl
shutdown" and "xl destroy" of both a PV and HVM guest therefore 4
pages should cover the majority of important cases.
This fixes http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1719.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reported-by: Zheng, Shaohui <shaohui.zheng@intel.com>
Tested-by: Haitao Shan <maillists.shan@gmail.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
(Modified version of this patch, with updated #includes in
xc_hcall_buf.c to fix stubdomain build.)
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Ian Campbell