Messages in this thread | | | Date | Wed, 06 May 2015 22:37:28 -0400 | From | Waiman Long <> | Subject | Re: [PATCH 0/13] Parallel struct page initialisation v4 |
| |
On 05/06/2015 01:58 PM, Waiman Long wrote: > On 05/06/2015 06:22 AM, Mel Gorman wrote: >> On Wed, May 06, 2015 at 08:12:46AM +0100, Mel Gorman wrote: >>> On Tue, May 05, 2015 at 03:25:49PM -0700, Andrew Morton wrote: >>>> On Tue, 5 May 2015 23:13:29 +0100 Mel Gorman<mgorman@suse.de> wrote: >>>> >>>>>> Alternatively, the page allocator can go off and synchronously >>>>>> initialize some pageframes itself. Keep doing that until the >>>>>> allocation attempt succeeds. >>>>>> >>>>> That was rejected during review of earlier attempts at this >>>>> feature on >>>>> the grounds that it impacted allocator fast paths. >>>> eh? Changes are only needed on the allocation-attempt-failed path, >>>> which is slow-path. >>> We'd have to distinguish between falling back to other zones because >>> the >>> high zone is artifically exhausted and normal ALLOC_BATCH >>> exhaustion. We'd >>> also have to avoid falling back to remote nodes prematurely. While I >>> have >>> not tried an implementation, I expected they would need to be in the >>> fast >>> paths unless I used jump labels to get around it. I'm going to try >>> altering >>> when we initialise instead so that it happens earlier. >>> >> Which looks as follows. Waiman, a test on the 24TB machine would be >> appreciated again. This patch should be applied instead of "mm: meminit: >> Take into account that large system caches scale linearly with memory" >> >> ---8<--- >> mm: meminit: Finish initialisation of memory before basic setup >> >> Waiman Long reported that 24TB machines hit OOM during basic setup when >> struct page initialisation was deferred. One approach is to >> initialise memory >> on demand but it interferes with page allocator paths. This patch >> creates >> dedicated threads to initialise memory before basic setup. It then >> blocks >> on a rw_semaphore until completion as a wait_queue and counter is >> overkill. >> This may be slower to boot but it's simplier overall and also gets >> rid of a >> lot of section mangling which existed so kswapd could do the >> initialisation. >> >> Signed-off-by: Mel Gorman<mgorman@suse.de> >> > > This patch moves the deferred meminit from kswapd to its own kernel > threads started after smp_init(). However, the hash table allocation > was done earlier than that. It seems like it will still run out of > memory in the 24TB machine that I tested on. > > I will certainly try it out, but I doubt it will solve the problem on > its own.
It turns out that the two new patches did work on the 24-TB DragonHawk without the "mm: meminit: Take into account that large system caches scale linearly with memory" patch. The bootup time was 357s which was just a few seconds slower than the other bootup times that I sent you yesterday.
BTW, do you want to change the following log message as kswapd will no longer be the one doing deferred meminit?
kswapd 0 initialised 396098436 pages in 6024ms
Cheers, Longman
| |