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[SCM] Hurd branch, master, updated. v0.5-249-g1a3d809
From: |
Justus Winter |
Subject: |
[SCM] Hurd branch, master, updated. v0.5-249-g1a3d809 |
Date: |
Tue, 13 May 2014 14:54:10 +0000 |
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the project "Hurd".
The branch, master has been updated
via 1a3d809146c95cd138bad7bd42eb923af0a23493 (commit)
via 134b450cb65b1986c78e0b292cff78c2f1882a2b (commit)
from 261d957ebe4cf16aed76eed24b5bfd32f1f5a79a (commit)
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- Log -----------------------------------------------------------------
commit 1a3d809146c95cd138bad7bd42eb923af0a23493
Author: Justus Winter <address@hidden>
Date: Thu May 8 16:43:11 2014 +0200
libihash: reduce the default maximum load factor to 75%
The performance of hash tables depend critically on a low number of
hash collisions. As the table fills up, the chance of collisions
necessarily raises.
Previously, libihash resized the hash table when the load exceeded
80%. This seems a bit optimistic (e. g. java.util.Hashtable uses 75%
as default).
* libihash/ihash.h (HURD_IHASH_MAX_LOAD_DEFAULT): Set to 75.
commit 134b450cb65b1986c78e0b292cff78c2f1882a2b
Author: Justus Winter <address@hidden>
Date: Thu Apr 24 17:44:14 2014 +0200
ext2fs: cache the superblock
Previously, the superblock was mmaped and a pointer stored in sblock
by map_hypermetadata. This memory is backed by our disk pager.
This is rather unfortunate, as this means that whenever we read a
value from that location, we might generate a request our disk pager.
This amplifies the so-called thread-storm problem.
Rather than relying on a mmaped region of memory, just use the data
loaded by get_hypermetadata.
* ext2fs/hyper.c (get_hypermetadata): Do not free sblock.
(mapped_sblock): New variable.
(map_hypermetadata): Map the superblock to mapped_sblock instead.
(diskfs_set_hypermetadata): Copy superblock into mapped_superblock.
* ext2fs/ext2fs.h (get_hypermetadata, map_hypermetadata): Adjust
comments accordingly.
-----------------------------------------------------------------------
Summary of changes:
ext2fs/ext2fs.h | 8 ++++++--
ext2fs/hyper.c | 19 +++++++++++--------
libihash/ihash.h | 2 +-
3 files changed, 18 insertions(+), 11 deletions(-)
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