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Message-ID: <20090525051521.GC23032@elte.hu> Date: Mon, 25 May 2009 07:15:21 +0200 From: Ingo Molnar <mingo@...e.hu> To: Yinghai Lu <yinghai@...nel.org> Cc: Pekka J Enberg <penberg@...helsinki.fi>, Rusty Russell <rusty@...tcorp.com.au>, Linus Torvalds <torvalds@...ux-foundation.org>, "H. Peter Anvin" <hpa@...or.com>, Jeff Garzik <jgarzik@...ox.com>, Alexander Viro <viro@....linux.org.uk>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl> Subject: Re: [GIT PULL] scheduler fixes * Yinghai Lu <yinghai@...nel.org> wrote: > Ingo Molnar wrote: > > * Yinghai Lu <yinghai@...nel.org> wrote: > > > >> Pekka J Enberg wrote: > >>> On Mon, 18 May 2009, Linus Torvalds wrote: > >>>>>> I hate that stupid bootmem allocator. I suspect we seriously > >>>>>> over-use it, and that we _should_ be able to do the SL*B init > >>>>>> earlier. > >>>>> Hm, tempting thought - not sure how to pull it off though. > >>>> As far as I can recall, one of the things that historically made us want > >>>> to use the bootmem allocator even relatively late was that the real SLAB > >>>> allocator had to wait until all the node information etc was initialized. > >>>> > >>>> That's pretty damn late. And I wonder if SLUB (and SLOB) might not need a > >>>> lot less initialization, and work much earlier. Something like that might > >>>> be the final nail in the coffin for SLAB, and convince me to just say > >>>> 'we don't support it any more". > >>> Ingo, here's a patch that boots UMA+SMP+SLUB x86-64 kernel on qemu all > >>> the way to userspace. It probably breaks bunch of things for now but > >>> something for you to play with if you want. > >>> > >> updated with tip/master. also add change to cpupri_init > >> otherwise will get > >> [ 0.000000] Memory: 523096612k/537526272k available (10461k kernel code, 656156k absent, 13773504k reserved, 7186k data, 2548k init) > >> [ 0.000000] SLUB: Genslabs=14, HWalign=64, Order=0-3, MinObjects=0, CPUs=32, Nodes=8 > >> [ 0.000000] ------------[ cut here ]------------ > >> [ 0.000000] WARNING: at kernel/lockdep.c:2282 lockdep_trace_alloc+0xaf/0xee() > >> [ 0.000000] Hardware name: Sun Fire X4600 M2 > >> [ 0.000000] Modules linked in: > >> [ 0.000000] Pid: 0, comm: swapper Not tainted 2.6.30-rc6-tip-01778-g0afdd0f-dirty #259 > >> [ 0.000000] Call Trace: > >> [ 0.000000] [<ffffffff810a0274>] ? lockdep_trace_alloc+0xaf/0xee > >> [ 0.000000] [<ffffffff81075ab0>] warn_slowpath_common+0x88/0xcb > >> [ 0.000000] [<ffffffff81075b15>] warn_slowpath_null+0x22/0x38 > >> [ 0.000000] [<ffffffff810a0274>] lockdep_trace_alloc+0xaf/0xee > >> [ 0.000000] [<ffffffff8110301b>] kmem_cache_alloc_node+0x38/0x14d > >> [ 0.000000] [<ffffffff813ec548>] ? alloc_cpumask_var_node+0x4a/0x10a > >> [ 0.000000] [<ffffffff8109eb61>] ? lockdep_init_map+0xb9/0x564 > >> [ 0.000000] [<ffffffff813ec548>] alloc_cpumask_var_node+0x4a/0x10a > >> [ 0.000000] [<ffffffff813ec62c>] alloc_cpumask_var+0x24/0x3a > >> [ 0.000000] [<ffffffff819e6306>] cpupri_init+0x7f/0x112 > >> [ 0.000000] [<ffffffff819e5a30>] init_rootdomain+0x72/0xb7 > >> [ 0.000000] [<ffffffff821facce>] sched_init+0x109/0x660 > >> [ 0.000000] [<ffffffff82203082>] ? kmem_cache_init+0x193/0x1b2 > >> [ 0.000000] [<ffffffff821dfd7a>] start_kernel+0x218/0x3f3 > >> [ 0.000000] [<ffffffff821df2a9>] x86_64_start_reservations+0xb9/0xd4 > >> [ 0.000000] [<ffffffff821df3b2>] x86_64_start_kernel+0xee/0x109 > >> [ 0.000000] ---[ end trace a7919e7f17c0a725 ]--- > >> > >> works with 8 sockets numa amd64 box. > >> > >> YH > >> > >> --- > >> init/main.c | 28 ++++++++++++++++------------ > >> kernel/irq/handle.c | 23 ++++++++--------------- > >> kernel/sched.c | 34 +++++++++++++--------------------- > >> kernel/sched_cpupri.c | 9 ++++++--- > >> mm/slub.c | 17 ++++++++++------- > >> 5 files changed, 53 insertions(+), 58 deletions(-) > > > > Very nice! > > > > Would it be possible to restructure things to move kmalloc init to > > before IRQ init as well? We have a couple of uglinesses there too. > > > > Conceptually, memory should be the first thing set up in general, in > > a kernel. It does not need IRQs, timers, the scheduler or any of the > > IO facilities and abstractions. All of them need memory though - and > > as Linux scales to more and more hardware via the same single image, > > so will we get more and more dynamic concepts like cpumask_var_t and > > sparse-irqs, which want to allocate very early. > > Pekka's patch already made kmalloc before early_irq_init()/init_IRQ... > > we can clean up alloc_desc_masks and > alloc_cpumask_var_node could be much simplified too. That's nice! Ok, i think this all looks pretty realistic - but there's quite a bit of layering on top of pending changes in the x86 and irq trees. We could do this on top of those topic branches in -tip, and rebase in the merge window. Or delay it to .32. ... plus i think we are _very_ close to being able to remove all of bootmem on x86 (with some compatibility/migration mechanism in place). Which bootmem calls do we have before kmalloc init with Pekka's patch applied? I think it's mostly the page table init code. ( beyond the page allocator internal use - where we could use straight e820 based APIs that clip memory off from the beginning of existing e820 RAM ranges - enriched with NUMA/SRAT locality info. ) Ingo -- 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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