Re: [Qemu-devel] [RFC V4 00/30] QCOW2 deduplication

["Benoît Canet" <benoit.canet@irqsave.net>]

Hello,

I started to write the deduplication metrics code in order to be able
to design asynchronous deduplication.

I am looking for a way to create a metric allowing deduplication to be paused
or resumed on a given threshold.

Does anyone have a sugestion regarding the metric that could be used for this ?

Best regards

Benoît

> Le Wednesday 02 Jan 2013 à 17:16:03 (+0100), Benoît Canet a écrit :
> This patchset is a cleanup of the previous QCOW2 deduplication rfc.
> 
> One can compile and install https://github.com/wernerd/Skein3Fish and use the
> --enable-skein-dedup configure option in order to use the faster skein HASH.
> 
> Images must be created with "-o dedup=[skein|sha256]" in order to activate the
> deduplication in the image.
> 
> Deduplication is now fast enough to be usable.
> 
> v4: Fix and complete qcow2 spec [Stefan]
>     Hash the hash_algo field in the header extension [Stefan]
>     Fix qcow2 spec [Eric]
>     Remove pointer to hash and simplify hash memory management [Stefan]
>     Rename and move qcow2_read_cluster_data to qcow2.c [Stefan]
>     Document lock dropping behaviour of the previous function [Stefan]
>     cleanup qcow2_dedup_read_missing_cluster_data [Stefan]
>     rename *_offset to *_sect [Stefan]
>     add a ./configure check for ssl [Stefan]
>     Replace openssl by gnutls [Stefan]
>     Implement Skein hashes
>     Rewrite pretty every qcow2-dedup.c commits after Add
>        qcow2_dedup_read_missing_and_concatenate to simplify the code
>     Use 64KB deduplication hash block to reduce allocation flushes
>     Use 64KB l2 tables to reduce allocation flushes [breaks compatibility]
>     Use lazy refcounts to avoid qcow2_cache_set_dependency loops resultings
>        in frequent caches flushes
>     Do not create and load dedup RAM structures when bdrs->read_only is true
> 
> v3: make it work barely
>     replace kernel red black trees by gtree.
> 
> *** BLURB HERE ***
> 
> Benoît Canet (30):
>   qcow2: Add deduplication to the qcow2 specification.
>   qcow2: Add deduplication structures and fields.
>   qcow2: Add qcow2_dedup_read_missing_and_concatenate
>   qcow2: Make update_refcount public.
>   qcow2: Create a way to link to l2 tables when deduplicating.
>   qcow2: Add qcow2_dedup and related functions
>   qcow2: Add qcow2_dedup_store_new_hashes.
>   qcow2: Implement qcow2_compute_cluster_hash.
>   qcow2: Extract qcow2_dedup_grow_table
>   qcow2: Add qcow2_dedup_grow_table and use it.
>   qcow2: create function to load deduplication hashes at startup.
>   qcow2: Load and save deduplication table header extension.
>   qcow2: Extract qcow2_do_table_init.
>   qcow2-cache: Allow to choose table size at creation.
>   qcow2: Add qcow2_dedup_init and qcow2_dedup_close.
>   qcow2: Extract qcow2_add_feature and qcow2_remove_feature.
>   block: Add qemu-img dedup create option.
>   qcow2: Behave correctly when refcount reach 0 or 2^16.
>   qcow2: Integrate deduplication in qcow2_co_writev loop.
>   qcow2: Serialize write requests when deduplication is activated.
>   qcow2: Add verification of dedup table.
>   qcow2: Adapt checking of QCOW_OFLAG_COPIED for dedup.
>   qcow2: Add check_dedup_l2 in order to check l2 of dedup table.
>   qcow2: Do not overwrite existing entries with QCOW_OFLAG_COPIED.
>   qcow2: Integrate SKEIN hash algorithm in deduplication.
>   qcow2: Add lazy refcounts to deduplication to prevent
>     qcow2_cache_set_dependency loops
>   qcow2: Use large L2 table for deduplication.
>   qcow: Set dedup cluster block size to 64KB.
>   qcow2: init and cleanup deduplication.
>   qemu-iotests: Filter dedup=on/off so existing tests don't break.
> 
>  block/Makefile.objs          |    1 +
>  block/qcow2-cache.c          |   12 +-
>  block/qcow2-cluster.c        |  116 +++--
>  block/qcow2-dedup.c          | 1157 ++++++++++++++++++++++++++++++++++++++++++
>  block/qcow2-refcount.c       |  157 ++++--
>  block/qcow2.c                |  357 +++++++++++--
>  block/qcow2.h                |  120 ++++-
>  configure                    |   55 ++
>  docs/specs/qcow2.txt         |  100 +++-
>  include/block/block_int.h    |    1 +
>  tests/qemu-iotests/common.rc |    3 +-
>  11 files changed, 1955 insertions(+), 124 deletions(-)
>  create mode 100644 block/qcow2-dedup.c
> 
> -- 
> 1.7.10.4
>