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authorDan Magenheimer <dan.magenheimer@oracle.com>2011-09-27 08:47:58 -0600
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-10-14 12:36:08 -0400
commit38a1ed4f039db32b418007ac365076cf53647ebd (patch)
tree396d6b42817baa68d753f23a9784e81c5e23864d /include/xen
parent1f1503ba096d3a394d1454dac77467092ca996e6 (diff)
downloadop-kernel-dev-38a1ed4f039db32b418007ac365076cf53647ebd.zip
op-kernel-dev-38a1ed4f039db32b418007ac365076cf53647ebd.tar.gz
xen: Fix selfballooning and ensure it doesn't go too far
The balloon driver's "current_pages" is very different from totalram_pages. Self-ballooning needs to be driven by the latter. Also, Committed_AS doesn't account for pages used by the kernel so: 1) Add totalreserve_pages to Committed_AS for the normal target. 2) Enforce a floor for when there are little or no user-space threads using memory (e.g. single-user mode) to avoid OOMs. The floor function includes a "min_usable_mb" tuneable in case we discover later that the floor function is still too aggressive in some workloads, though likely it will not be needed. Changes since version 4: - change floor calculation so that it is not as aggressive; this version uses a piecewise linear function similar to minimum_target in the 2.6.18 balloon driver, but modified to add to totalreserve_pages instead of subtract from max_pfn, the 2.6.18 version causes OOMs on recent kernels because the kernel has expanded over time - change safety_margin to min_usable_mb and comment on its use - since committed_as does NOT include kernel space (and other reserved pages), totalreserve_pages is now added to committed_as. The result is less aggressive self-ballooning, but theoretically more appropriate. Changes since version 3: - missing include causes compile problem when CONFIG_FRONTSWAP is disabled - add comments after includes Changes since version 2: - missing include causes compile problem only on 32-bit Changes since version 1: - tuneable safety margin added [v5: avi.miller@oracle.com: still too aggressive, seeing some OOMs] [v4: konrad.wilk@oracle.com: fix compile when CONFIG_FRONTSWAP is disabled] [v3: guru.anbalagane@oracle.com: fix 32-bit compile] [v2: konrad.wilk@oracle.com: make safety margin tuneable] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> [v1: Altered description and added an extra include] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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