1 files changed, 49 insertions, 0 deletions
diff --git a/open_issues/performance/io_system.mdwn b/open_issues/performance/io_system.mdwn
new file mode 100644
index 00000000..0d41d3c7
--- /dev/null
+++ b/open_issues/performance/io_system.mdwn
@@ -0,0 +1,49 @@
+[[!meta copyright="Copyright © 2008, 2009, 2010 Free Software Foundation,
+Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license
+is included in the section entitled
+[[GNU Free Documentation License|/fdl]]."]]"""]]
+
+[[!meta title="I/O System"]]
+
+[[!tag open_issue_hurd]]
+
+The most obvious reason for the Hurd feeling slow compared to mainstream
+systems like GNU/Linux, is a low I/O system performance, in particular very
+slow hard disk access.
+
+The reason for this slowness is lack and/or bad implementation of common
+optimization techniques, like scheduling reads and writes to minimize head
+movement; effective block caching; effective reads/writes to partial blocks;
+reading/writing multiple blocks at once; and read-ahead.  The
+[[ext2_filesystem_server|hurd/translator/ext2fs]] might also need some
+optimizations at a higher logical level.
+
+The goal of this project is to analyze the current situation, and implement/fix
+various optimizations, to achieve significantly better disk performance. It
+requires understanding the data flow through the various layers involved in
+disk access on the Hurd ([[filesystem|hurd/virtual_file_system]],
+[[pager|hurd/libpager]], driver), and general experience with
+optimizing complex systems.  That said, the killing feature we are definitely
+missing is the read-ahead, and even a very simple implementation would bring
+very big performance speedups.
+
+Here are some real testcases:
+
+  * [[binutils_ld_64ksec]];
+
+  * running the Git testsuite which is mostly I/O bound;
+
+  * use [[TopGit]] on a non-toy repository.
+
+
+Possible mentors: Samuel Thibault (youpi)
+
+Exercise: Look through all the code involved in disk I/O, and try something
+easy to improve. It's quite likely though that you will find nothing obvious --
+in this case, please contact us about a different exercise task.