On Mon, 2005-10-10 at 15:30 -0400, Silbermann, Martine wrote: > * Memory hotplug common regressions - testing plan. > Please take a few minutes to read the proposed testing plan (issued from > the discussions we had in the last 2 meetings) and provide your > comments/suggestions/additions either by mail or live during tomorrow's > meeting. > http://www.developer.osdl.org/maryedie/HOTPLUG/planning/hotplug_memory_t > est_plan_status.html The description of the fragmentation tests looks a bit too complex to me. There are some less invasive You measure slab fragmentation by looking at the first two columns of /proc/slabinfo. The first is the number of objects which have been handed outside the slab. The second is the number of objects that have already have memory in the slab allocated to them, but have not been allocated outside the slab cache itself. The first column may never be larger than the second. The farther apart the values in the two columns, the more slab fragmentation you have. To measure fragmentation of the buddy allocator, you must use a different method: look at /proc/buddyinfo. The first column is the number of (2^0 * PAGE_SIZE) pages available. The second column is the number of (2^1 * PAGE_SIZE) pages available. These go all the way up to MAX_ORDER-1. You must force the system to free up as many pages as it can, then look at buddyinfo again. A perfectly non-fragmenting system will have no column with a value of greater than 1. Any column with a larger value is an indicator of fragmentation. Larger number is columns farther to to the left indicate larger levels of fragmentation. -- Dave
