Hi, I hope someone can enlighten me on the behaviour of malloc with respect to 'Active' memory. Circumstances: I have installed FC4 x86_64 on a Dual Opteron machine with 8GB of physical memory. I am planning to use this box solely for hosting a large MySQL database, so I configured MySQL 4.1 (official x86_64, glibc2.3 rpm) to use 7GB for it's InnoDB buffer pool (innodb_buffer_pool_size). So far this works flawlessly. The problem: After doing several compiles on the machine (it is my only x86_64 machine at the moment), some memory is used by the kernel for several uses. Let's have a look at /proc/meminfo: MemTotal: 8124080 kB MemFree: 385772 kB Buffers: 201632 kB Cached: 661568 kB SwapCached: 0 kB Active: 5958788 kB Inactive: 1463764 kB HighTotal: 0 kB HighFree: 0 kB LowTotal: 8124080 kB LowFree: 385772 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB Mapped: 270844 kB Slab: 284044 kB CommitLimit: 4062040 kB Committed_AS: 2618264 kB PageTables: 16772 kB VmallocTotal: 34359738367 kB VmallocUsed: 288 kB VmallocChunk: 34359738043 kB HugePages_Total: 0 HugePages_Free: 0 Hugepagesize: 2048 kB Only roughly 375 MB 'free' memory left. Not a problem by itself, the kernel is expected to make good use of the memory it can get. However when I stop MySQL and then try to restart it, I get the following error: 050726 13:56:21 InnoDB: Error: cannot allocate 7340048384 bytes of InnoDB: memory with malloc! Total allocated memory InnoDB: by InnoDB 78086952 bytes. Operating system errno: 12 InnoDB: Check if you should increase the swap file or InnoDB: ulimits of your operating system. InnoDB: On FreeBSD check you have compiled the OS with InnoDB: a big enough maximum process size. InnoDB: We keep retrying the allocation for 60 seconds... InnoDB: Fatal error: cannot allocate the memory for the buffer pool Even after hours later I cannot reclaim the memory. Only after decreasing the InnoDB buffer pool to roughly 1.6GB (found this by trial and error), MySQL can be successfully started again. Now it sound rather ridiculous that I can use only 1.6GB of 8GB physical memory. Can anybody explain where the rest of the memory has gone? According to /proc/meminfo output I would guess it be in the 'Active' region: 'Active: Memory that has been used more recently and usually not reclaimed unless absolutely necessary.' (http://www.redhat.com/advice/tips/meminfo.html) How do I reclaim this memory? I need it for MySQL. The only way I have found so far is rebooting the machine, but I cannot imagine that would be the ultimate solution. Some snippets of MySQL code: ulint n, /* in: number of bytes to allocate */ ret = malloc(n + sizeof(ut_mem_block_t)); if (ret == NULL && retry_count < 60) { if (retry_count == 0) { ut_print_timestamp(stderr); fprintf(stderr, " InnoDB: Error: cannot allocate %lu bytes of\n" Thanks for your time. Best regards, -- Matthijs van der Klip System Administrator Spill E-Projects The Netherlands
