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authorVitaly Wool <vitaly.wool@konsulko.com>2019-11-30 17:56:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:07 -0800
commit4a3ac9311dac3850d1fbaa8bcad4cf10c4fc6296 (patch)
treeee209f93769d4fca9e7b45069b7c0149368506ae /mm/mempolicy.c
parent204cb79ad42f015312a5bbd7012d09c93d9b46fb (diff)
downloadlinux-4a3ac9311dac3850d1fbaa8bcad4cf10c4fc6296.tar.bz2
mm/z3fold.c: add inter-page compaction
For each page scheduled for compaction (e. g. by z3fold_free()), try to apply inter-page compaction before running the traditional/ existing intra-page compaction. That means, if the page has only one buddy, we treat that buddy as a new object that we aim to place into an existing z3fold page. If such a page is found, that object is transferred and the old page is freed completely. The transferred object is named "foreign" and treated slightly differently thereafter. Namely, we increase "foreign handle" counter for the new page. Pages with non-zero "foreign handle" count become unmovable. This patch implements "foreign handle" detection when a handle is freed to decrement the foreign handle counter accordingly, so a page may as well become movable again as the time goes by. As a result, we almost always have exactly 3 objects per page and significantly better average compression ratio. [cai@lca.pw: fix -Wunused-but-set-variable warnings] Link: http://lkml.kernel.org/r/1570542062-29144-1-git-send-email-cai@lca.pw [vitalywool@gmail.com: avoid subtle race when freeing slots] Link: http://lkml.kernel.org/r/20191127152118.6314b99074b0626d4c5a8835@gmail.com [vitalywool@gmail.com: compact objects more accurately] Link: http://lkml.kernel.org/r/20191127152216.6ad33745a21ba71c53606acb@gmail.com [vitalywool@gmail.com: protect handle reads] Link: http://lkml.kernel.org/r/20191127152345.8059852f60947686674d726d@gmail.com Link: http://lkml.kernel.org/r/20191006041457.24113-1-vitalywool@gmail.com Signed-off-by: Vitaly Wool <vitaly.vul@sony.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Henry Burns <henrywolfeburns@gmail.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mempolicy.c')
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