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Andres Lagar-Cavilla
59a36d66a5
Per page operations in the paging, sharing, and access tracking subsystems are all implemented with domctls (e.g. a domctl to evict one page, or to share one page). Under heavy load, the domctl path reveals a lack of scalability. The domctl lock serializes dom0's vcpus in the hypervisor. When performing thousands of per-page operations on dozens of domains, these vcpus will spin in the hypervisor. Beyond the aggressive locking, an added inefficiency of blocking vcpus in the domctl lock is that dom0 is prevented from re-scheduling any of its other work-starved processes. We retain the domctl interface for setting up and tearing down paging/sharing/mem access for a domain. But we migrate all the per page operations to use the memory_op hypercalls (e.g XENMEM_*). Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla> Signed-off-by: Adin Scannell <adin@scannell.ca> Acked-by: Tim Deegan <tim@xen.org> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com> Committed-by: Tim Deegan <tim@xen.org>
58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
/******************************************************************************
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*
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* xc_mem_event.c
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*
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* Interface to low-level memory event functionality.
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*
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* Copyright (c) 2009 Citrix Systems, Inc. (Patrick Colp)
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xc_private.h"
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int xc_mem_event_control(xc_interface *xch, domid_t domain_id, unsigned int op,
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unsigned int mode, void *page, void *ring_page)
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{
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DECLARE_DOMCTL;
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domctl.cmd = XEN_DOMCTL_mem_event_op;
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domctl.domain = domain_id;
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domctl.u.mem_event_op.op = op;
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domctl.u.mem_event_op.mode = mode;
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domctl.u.mem_event_op.shared_addr = (unsigned long)page;
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domctl.u.mem_event_op.ring_addr = (unsigned long)ring_page;
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return do_domctl(xch, &domctl);
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}
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int xc_mem_event_memop(xc_interface *xch, domid_t domain_id,
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unsigned int op, unsigned int mode,
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uint64_t gfn, void *buffer)
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{
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xen_mem_event_op_t meo;
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memset(&meo, 0, sizeof(meo));
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meo.op = op;
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meo.domain = domain_id;
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meo.gfn = gfn;
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meo.buffer = (unsigned long) buffer;
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return do_memory_op(xch, mode, &meo, sizeof(meo));
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}
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