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Date: Thu, 14 May 2009 14:05:02 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Michał Nazarewicz <m.nazarewicz@...sung.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, m.szyprowski@...sung.com, kyungmin.park@...sung.com, linux-mm@...ck.org Subject: Re: [PATCH] Physical Memory Management [0/1] On Thu, 2009-05-14 at 13:48 +0200, Michał Nazarewicz wrote: > > On Thu, 2009-05-14 at 11:00 +0200, Michał Nazarewicz wrote: > >> PMM solves this problem since the buffers are allocated when they > >> are needed. > > On Thu, 14 May 2009 13:20:02 +0200, Peter Zijlstra wrote: > > Ha - only when you actually manage to allocate things. Physically > > contiguous allocations are exceedingly hard once the machine has been > > running for a while. > > PMM reserves memory during boot time using alloc_bootmem_low_pages(). > After this is done, it can allocate buffers from reserved pool. > > The idea here is that there are n hardware accelerators, each > can operate on 1MiB blocks (to simplify assume that's the case). > However, we know that at most m < n devices will be used at the same > time so instead of reserving n MiBs of memory we reserve only m MiBs. And who says your pre-allocated pool won't fragment with repeated PMM use? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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