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