Re: [xwiki-users] MySQL storage using MyISAM engine.

BTW a few more interesting links and excepts on this subject. Seems like if one can devote a certain amount of RAM to Mysql, this could potentially be a performace win for a larger Xwiki install: http://www.basysadmin.com/procedures.html http://www.cyberciti.biz/files/linux-kernel/Documentation/vm/hugetlbpage.txt http://docs.sun.com/source/mysql-refman-5.0/optimization.html http://www.cyberciti.biz/tips/linux-hugetlbfs-and-mysql-performance.html A pplications that perform a lot of memory accesses (several GBs) may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses. HugeTLBfs is memory management feature offered in Linux kernel, which is valuable for applications that use a large virtual address space. It is especially useful for database applications such as MySQL, Oracle and others. Other server software that uses the prefork or similar (e.g. Apache web server) model will also benefit. The CPU's Translation Lookaside Buffer (TLB) is a small cache used for storing virtual-to-physical mapping information. By using the TLB, a translation can be performed without referencing the in-memory page table entry that maps the virtual address. However, to keep translations as fast as possible, the TLB is usually small. It is not uncommon for large memory applications to exceed the mapping capacity of the TLB. Users can use the huge page support in Linux kernel by either using the mmap system call or standard SYSv shared memory system calls (shmget, shmat). Only selected hardware and operating system support memory pages greater than the default 4KB. The following configuration tested on RHEL 5.3 64 bit using a stock kernel with tons of RAM and multiple CPUs. -- Niels http://nielsmayer.com