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Re: svn commit: r983474 - /subversion/branches/performance/subversion/libsvn_fs_fs/caching.c

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Fri, 13 Aug 2010 11:54:17 +0100

stefan2_at_apache.org writes:

> Author: stefan2
> Date: Sun Aug 8 19:41:11 2010
> New Revision: 983474
>
> URL: http://svn.apache.org/viewvc?rev=983474&view=rev
> Log:
> Memcached is often slower than a single file access.

Doesn't that depend on the type of filesystem used and the resources
allocated to memcached?

> Thus, it is not inefficient
> for most FSFS data structures: they can be read in a single request.

I don't understand this. Does "not inefficient" mean "efficient"? I
think you mean that for most FSFS data structures it is more efficient
to read from a file than to read from memcached.

> Use the
> membuffer cache for them instead.

I assume this is faster in your test environment. What sort of
environment is that? How does it compare to the enviroments that are
currently using memcached?

>
> * subversion/libsvn_fs_fs/caching.c
> (svn_fs_fs__initialize_caches): replace use of memcached with membuffer cache
> except for fulltext caches
>
> Modified:
> subversion/branches/performance/subversion/libsvn_fs_fs/caching.c
>
> Modified: subversion/branches/performance/subversion/libsvn_fs_fs/caching.c
> URL: http://svn.apache.org/viewvc/subversion/branches/performance/subversion/libsvn_fs_fs/caching.c?rev=983474&r1=983473&r2=983474&view=diff
> ==============================================================================
> --- subversion/branches/performance/subversion/libsvn_fs_fs/caching.c (original)
> +++ subversion/branches/performance/subversion/libsvn_fs_fs/caching.c Sun Aug 8 19:41:11 2010
> @@ -302,15 +302,15 @@ svn_fs_fs__initialize_caches(svn_fs_t *f
> * id_private_t + 3 strings for value, and the cache_entry); the
> * default pool size is 8192, so about a hundred should fit
> * comfortably. */
> - if (memcache)
> - SVN_ERR(svn_cache__create_memcache(&(ffd->rev_root_id_cache),
> - memcache,
> - serialize_id,
> - deserialize_id,
> - sizeof(svn_revnum_t),
> - apr_pstrcat(pool, prefix, "RRI",
> - NULL),
> - fs->pool));
> + if (get_global_membuffer_cache())
> + SVN_ERR(svn_cache__create_membuffer_cache(&(ffd->rev_root_id_cache),
> + get_global_membuffer_cache(),
> + svn_fs_fs__serialize_id,
> + svn_fs_fs__deserialize_id,
> + sizeof(svn_revnum_t),
> + apr_pstrcat(pool, prefix, "RRI",
> + NULL),
> + fs->pool));
> else
> SVN_ERR(svn_cache__create_inprocess(&(ffd->rev_root_id_cache),
> dup_id, sizeof(svn_revnum_t),
> @@ -322,15 +322,15 @@ svn_fs_fs__initialize_caches(svn_fs_t *f
>
> /* Rough estimate: revision DAG nodes have size around 320 bytes, so
> * let's put 16 on a page. */
> - if (memcache)
> - SVN_ERR(svn_cache__create_memcache(&(ffd->rev_node_cache),
> - memcache,
> - svn_fs_fs__dag_serialize,
> - svn_fs_fs__dag_deserialize,
> - APR_HASH_KEY_STRING,
> - apr_pstrcat(pool, prefix, "DAG",
> - NULL),
> - fs->pool));
> + if (get_global_membuffer_cache())
> + SVN_ERR(svn_cache__create_membuffer_cache(&(ffd->rev_node_cache),
> + get_global_membuffer_cache(),
> + svn_fs_fs__dag_serialize,
> + svn_fs_fs__dag_deserialize,
> + APR_HASH_KEY_STRING,
> + apr_pstrcat(pool, prefix, "DAG",
> + NULL),
> + fs->pool));
> else
> SVN_ERR(svn_cache__create_inprocess(&(ffd->rev_node_cache),
> svn_fs_fs__dag_dup_for_cache,
> @@ -342,15 +342,15 @@ svn_fs_fs__initialize_caches(svn_fs_t *f
>
>
> /* Very rough estimate: 1K per directory. */
> - if (memcache)
> - SVN_ERR(svn_cache__create_memcache(&(ffd->dir_cache),
> - memcache,
> - svn_fs_fs__dir_entries_serialize,
> - svn_fs_fs__dir_entries_deserialize,
> - APR_HASH_KEY_STRING,
> - apr_pstrcat(pool, prefix, "DIR",
> - NULL),
> - fs->pool));
> + if (get_global_membuffer_cache())
> + SVN_ERR(svn_cache__create_membuffer_cache(&(ffd->dir_cache),
> + get_global_membuffer_cache(),
> + svn_fs_fs__dir_entries_serialize,
> + svn_fs_fs__dir_entries_deserialize,
> + APR_HASH_KEY_STRING,
> + apr_pstrcat(pool, prefix, "DIR",
> + NULL),
> + fs->pool));
> else
> SVN_ERR(svn_cache__create_inprocess(&(ffd->dir_cache),
> dup_dir_listing, APR_HASH_KEY_STRING,
> @@ -362,15 +362,15 @@ svn_fs_fs__initialize_caches(svn_fs_t *f
>
> /* Only 16 bytes per entry (a revision number + the corresponding offset).
> Since we want ~8k pages, that means 512 entries per page. */
> - if (memcache)
> - SVN_ERR(svn_cache__create_memcache(&(ffd->packed_offset_cache),
> - memcache,
> - manifest_serialize,
> - manifest_deserialize,
> - sizeof(svn_revnum_t),
> - apr_pstrcat(pool, prefix, "PACK-MANIFEST",
> - NULL),
> - fs->pool));
> + if (get_global_membuffer_cache())
> + SVN_ERR(svn_cache__create_membuffer_cache(&(ffd->packed_offset_cache),
> + get_global_membuffer_cache(),
> + svn_fs_fs__serialize_manifest,
> + svn_fs_fs__deserialize_manifest,
> + sizeof(svn_revnum_t),
> + apr_pstrcat(pool, prefix, "PACK-MANIFEST",
> + NULL),
> + fs->pool));
> else
> SVN_ERR(svn_cache__create_inprocess(&(ffd->packed_offset_cache),
> dup_pack_manifest, sizeof(svn_revnum_t),
>
>

-- 
Philip
Received on 2010-08-13 12:55:07 CEST

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