From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 24 May 2007 12:22:51 -0500 From: Matt Mackall Subject: Re: [patch 1/3] slob: rework freelist handling Message-ID: <20070524172251.GX11115@waste.org> References: <20070523183224.GD11115@waste.org> <20070523195824.GF11115@waste.org> <20070523210612.GI11115@waste.org> <20070523224206.GN11115@waste.org> <20070524061153.GP11115@waste.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Nick Piggin , Andrew Morton , Linux Memory Management List List-ID: On Thu, May 24, 2007 at 09:36:16AM -0700, Christoph Lameter wrote: > On Thu, 24 May 2007, Matt Mackall wrote: > > > So, here's three possible approaches to this issue: > > > > A) Continue to ignore it. Doing something about it would add > > complexity and it's not clear that it's a win. > > > > B) Set NR_SLAB_RECLAIMABLE to 1. If the VM starts checking that to > > decide whether it should call shrinkers, things will continue to work. > > Increment and decrement NR_SLAB_UNRECLAIMABLE when we grow/shrink the > > SLOB pool. This is probably 3 lines of code total. > > > > C) Fake NR_SLAB_RECLAIMABLE/NR_SLAB_UNRECLAIMABLE based on actual > > allocs and slab flags such that they sum to the total pages in the > > SLOB pool. This would need a third global counter in bytes of how many > > allocs we had in the "reclaimable" slabs. Probably 10-20 lines of > > code of marginal utility. > > > > So, nothing insurmountable here. Just not convinced we should bother. > > But the cost of B is so low, perhaps I might as well. > > D) Do the right thing and implement the counters. That's C) above. But you haven't answered the real question: why bother? RECLAIMABLE is a bogus number and the VM treats it as such. We can make no judgment on how much memory we can actually reclaim from looking at reclaimable - it might very easily all be pinned. RECLAIMABLE+UNRECLAIMABLE is a more interesting number - the total memory used by the allocator. But that's mostly interesting as a user-level diagnostic. -- Mathematics is the supreme nostalgia of our time. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org