Creating key caches of size greater than 2GB

[Shaji Sebastian]

I am attempting to create a key cache of size greater than 2GB on mysql 4.1.11 on Redhat Enterprise 3 running on a 32 bit Intel server with 4GB of memory. Since the kernel is in 3GB/1GB memory mode, I know that the mysql process cannot allocate more than 3GB of memory. However I am unable to have it allocate more than 2 GB of memory which is surprising.

I have the mysql configuration appended to this message. I ask it to load all the indexes of a large table into the cache. After about two minutes the command completes successfully. However the number of key_blocks_used is 1833165 which is less than 2GB of memory. key_blocks_unused is 0. The indexes are larger than that. Subsequently a query on the table which only uses the indexes of that cache is made and the number of key_reads goes up by about 1647 blocks, showing that the cache has not fully loaded the indexes. The memory used by mysql is only around 2GB (as seen in top).

I don't understand why I am not able to load closer to 3GB worth of data into the cache. Any ideas?

Another question I have is how one can view status variables like key_buffers_unused, key_read_requests for a named cache.

Thanks.

my.cnf fragment follows:
[mysqld]
port = 8084
...
skip-innodb
skip-locking
bulk_insert_buffer_size = 16M
key_buffer = 3584M
max_allowed_packet = 1M
table_cache = 512
sort_buffer_size = 64M
read_buffer_size = 32M
myisam_sort_buffer_size = 64M
thread_cache = 8
query_cache_size = 32M
# Try number of CPU's*2 for thread_concurrency
thread_concurrency = 8