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From 7fa1062d4c4f6581bbe53a68f4cdd78558bcf5e3 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 6 Dec 2018 17:12:40 +0000
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Subject: [PATCH 15/15] qcow2: Fix cache-clean-interval documentation
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20181206171240.5674-16-kwolf@redhat.com>
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Patchwork-id: 83298
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O-Subject: [RHEL-8.0 qemu-kvm PATCH 15/15] qcow2: Fix cache-clean-interval documentation
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Bugzilla: 1656507
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Leonid Bloch <lbloch@janustech.com>
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Fixing cache-clean-interval documentation following the recent change to
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a default of 600 seconds on supported plarforms (only Linux currently).
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Signed-off-by: Leonid Bloch <lbloch@janustech.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit e3a7b4556ee33feba2b396769a9c8354be06b024)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 docs/qcow2-cache.txt | 20 ++++++++++----------
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 qapi/block-core.json |  3 ++-
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 qemu-options.hx      |  3 ++-
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 3 files changed, 14 insertions(+), 12 deletions(-)
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diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
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index 59358b8..c459bf5 100644
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--- a/docs/qcow2-cache.txt
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+++ b/docs/qcow2-cache.txt
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@@ -202,18 +202,18 @@ Reducing the memory usage
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 It is possible to clean unused cache entries in order to reduce the
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 memory usage during periods of low I/O activity.
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-The parameter "cache-clean-interval" defines an interval (in seconds).
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-All cache entries that haven't been accessed during that interval are
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-removed from memory.
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+The parameter "cache-clean-interval" defines an interval (in seconds),
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+after which all the cache entries that haven't been accessed during the
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+interval are removed from memory. Setting this parameter to 0 disables this
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+feature.
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-This example removes all unused cache entries every 15 minutes:
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+The following example removes all unused cache entries every 15 minutes:
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    -drive file=hd.qcow2,cache-clean-interval=900
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-If unset, the default value for this parameter is 600. Setting it to 0
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-disables this feature.
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+If unset, the default value for this parameter is 600 on platforms which
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+support this functionality, and is 0 (disabled) on other platforms.
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-Note that this functionality currently relies on the MADV_DONTNEED
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-argument for madvise() to actually free the memory. This is a
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-Linux-specific feature, so cache-clean-interval is not supported in
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-other systems.
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+This functionality currently relies on the MADV_DONTNEED argument for
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+madvise() to actually free the memory. This is a Linux-specific feature,
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+so cache-clean-interval is not supported on other systems.
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diff --git a/qapi/block-core.json b/qapi/block-core.json
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index 5318c9b..db47fb8 100644
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--- a/qapi/block-core.json
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+++ b/qapi/block-core.json
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@@ -2867,7 +2867,8 @@
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 #
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 # @cache-clean-interval:  clean unused entries in the L2 and refcount
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 #                         caches. The interval is in seconds. The default value
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-#                         is 600, and 0 disables this feature. (since 2.5)
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+#                         is 600 on supporting platforms, and 0 on other
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+#                         platforms. 0 disables this feature. (since 2.5)
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 #
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 # @encrypt:               Image decryption options. Mandatory for
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 #                         encrypted images, except when doing a metadata-only
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diff --git a/qemu-options.hx b/qemu-options.hx
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index 05fabf3..683ab0d 100644
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--- a/qemu-options.hx
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+++ b/qemu-options.hx
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@@ -767,7 +767,8 @@ it which is not used for the L2 cache)
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 @item cache-clean-interval
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 Clean unused entries in the L2 and refcount caches. The interval is in seconds.
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-The default value is 600. Setting it to 0 disables this feature.
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+The default value is 600 on supporting platforms, and 0 on other platforms.
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+Setting it to 0 disables this feature.
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 @item pass-discard-request
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 Whether discard requests to the qcow2 device should be forwarded to the data
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-- 
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1.8.3.1
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