On Wed, 24 Jan 2007 18:41:27 -0800 (PST) Christoph Lameter <[EMAIL PROTECTED]> wrote: > > But I can't think of the way to show that. > > == > > [EMAIL PROTECTED] src]$ free > > total used free shared buffers cached > > Mem: 741604 724628 16976 0 62700 564600 > > -/+ buffers/cache: 97328 644276 > > Swap: 1052216 2532 1049684 > > == > > Could we call the free memory "unused memory" and not talk about free > memory at all? > Ah, maybe it's better.
I met several memory troubles in user's systems in these days. (on older kernels) Thousands/hundreds of process works on it. When I explain the cutomers about memory management, I devides memory into.. (1) unused memory --- memory which is not used, in free-list of zones. (2) reclaimable memory --- page cache, which is reclaimable clean pages --- can be reclaimed soon dirty pages --- need to be written back *BUT* busy pages are unreclaimable. (3) swappable memory --- user process's pages. basically reclaimable if swap is available. shmem pages are included here. (4) locked memory --- mlocked memory, which is not reclaimable(but movable) (5) kernel memory --- used by kernel, (and we can't see how many pages are reclaimable) We can know the amount of (1) and (5) and total memory. Basically, (3) = (Total) - (2) - (1). busy data-set of (2)(3) is not reclaimable. but the amount of busy data-set is unknown. Many users takes log of 'ps' or 'sar' to estimate their memory usage. (and sometimes page-cache of 'log-file' eats their memory.....) The amount of (4) is unknown. But there was a system with 6GB of 8GB memory was mlocked (--; and OOM works. I'm sorry that I can't catch up how the current kernel can show memory usage. I should investigate that. FYI: Because some customers are migrated from mainframes, they want to control almost all features in OS, IOW, designing memory usages. -Kame - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/