From: David Rientjes <rientjes@google.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Fengguang Wu <fengguang.wu@intel.com>, David Cohen <david.a.cohen@linux.intel.com>, Al Viro <viro@zeniv.linux.org.uk>, Damien Ramonda <damien.ramonda@intel.com>, Jan Kara <jack@suse.cz>, Linus <torvalds@linux-foundation.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Date: Thu, 6 Feb 2014 15:58:17 -0800 (PST) [thread overview] Message-ID: <alpine.DEB.2.02.1402061557210.5061@chino.kir.corp.google.com> (raw) In-Reply-To: <alpine.DEB.2.02.1402061537180.3441@chino.kir.corp.google.com> On Thu, 6 Feb 2014, David Rientjes wrote: > > > > > +#define MAX_REMOTE_READAHEAD 4096UL > Normally it wouldn't matter because there's no significant downside to it > racing, things like mempolicies which use numa_node_id() extensively would > result in, oops, a page allocation on the wrong node. > > This stands out to me, though, because you're expecting the calculation to > be correct for a specific node. > > The patch is still wrong, though, it should just do > > int node = ACCESS_ONCE(numa_mem_id()); > return min(nr, (node_page_state(node, NR_INACTIVE_FILE) + > node_page_state(node, NR_FREE_PAGES)) / 2); > > since we want to readahead based on the cpu's local node, the comment > saying we're reading ahead onto "remote memory" is wrong since a > memoryless node has local affinity to numa_mem_id(). > Oops, forgot about the MAX_REMOTE_READAHEAD which needs to be factored in as well, but this handles the bound on local node's statistics.
WARNING: multiple messages have this Message-ID (diff)
From: David Rientjes <rientjes@google.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Fengguang Wu <fengguang.wu@intel.com>, David Cohen <david.a.cohen@linux.intel.com>, Al Viro <viro@zeniv.linux.org.uk>, Damien Ramonda <damien.ramonda@intel.com>, Jan Kara <jack@suse.cz>, Linus <torvalds@linux-foundation.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Date: Thu, 6 Feb 2014 15:58:17 -0800 (PST) [thread overview] Message-ID: <alpine.DEB.2.02.1402061557210.5061@chino.kir.corp.google.com> (raw) In-Reply-To: <alpine.DEB.2.02.1402061537180.3441@chino.kir.corp.google.com> On Thu, 6 Feb 2014, David Rientjes wrote: > > > > > +#define MAX_REMOTE_READAHEAD 4096UL > Normally it wouldn't matter because there's no significant downside to it > racing, things like mempolicies which use numa_node_id() extensively would > result in, oops, a page allocation on the wrong node. > > This stands out to me, though, because you're expecting the calculation to > be correct for a specific node. > > The patch is still wrong, though, it should just do > > int node = ACCESS_ONCE(numa_mem_id()); > return min(nr, (node_page_state(node, NR_INACTIVE_FILE) + > node_page_state(node, NR_FREE_PAGES)) / 2); > > since we want to readahead based on the cpu's local node, the comment > saying we're reading ahead onto "remote memory" is wrong since a > memoryless node has local affinity to numa_mem_id(). > Oops, forgot about the MAX_REMOTE_READAHEAD which needs to be factored in as well, but this handles the bound on local node's statistics. -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-02-06 23:58 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-01-22 10:53 [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Raghavendra K T 2014-01-22 10:53 ` Raghavendra K T 2014-02-03 8:30 ` Raghavendra K T 2014-02-03 8:30 ` Raghavendra K T 2014-02-06 22:51 ` Andrew Morton 2014-02-06 22:51 ` Andrew Morton 2014-02-06 22:58 ` David Rientjes 2014-02-06 22:58 ` David Rientjes 2014-02-06 23:22 ` Andrew Morton 2014-02-06 23:22 ` Andrew Morton 2014-02-06 23:48 ` David Rientjes 2014-02-06 23:48 ` David Rientjes 2014-02-06 23:58 ` David Rientjes [this message] 2014-02-06 23:58 ` David Rientjes 2014-02-07 10:42 ` Raghavendra K T 2014-02-07 10:42 ` Raghavendra K T 2014-02-07 20:41 ` David Rientjes 2014-02-07 20:41 ` David Rientjes 2014-02-10 8:21 ` Raghavendra K T 2014-02-10 8:21 ` Raghavendra K T 2014-02-10 10:05 ` David Rientjes 2014-02-10 10:05 ` David Rientjes 2014-02-10 12:25 ` Raghavendra K T 2014-02-10 12:25 ` Raghavendra K T 2014-02-10 21:35 ` David Rientjes 2014-02-10 21:35 ` David Rientjes 2014-02-13 7:07 ` Raghavendra K T 2014-02-13 7:07 ` Raghavendra K T 2014-02-13 8:05 ` David Rientjes 2014-02-13 8:05 ` David Rientjes 2014-02-13 10:04 ` Raghavendra K T 2014-02-13 10:04 ` Raghavendra K T 2014-02-13 22:41 ` David Rientjes 2014-02-13 22:41 ` David Rientjes 2014-02-14 0:14 ` Nishanth Aravamudan 2014-02-14 0:14 ` Nishanth Aravamudan 2014-02-14 0:37 ` Linus Torvalds 2014-02-14 0:37 ` Linus Torvalds 2014-02-14 0:45 ` Andrew Morton 2014-02-14 0:45 ` Andrew Morton 2014-02-14 4:32 ` Nishanth Aravamudan 2014-02-14 4:32 ` Nishanth Aravamudan 2014-02-14 10:54 ` David Rientjes 2014-02-14 10:54 ` David Rientjes 2014-02-17 19:28 ` Nishanth Aravamudan 2014-02-17 19:28 ` Nishanth Aravamudan 2014-02-17 23:14 ` David Rientjes 2014-02-17 23:14 ` David Rientjes 2014-02-18 1:31 ` Nishanth Aravamudan 2014-02-18 1:31 ` Nishanth Aravamudan 2014-02-17 22:59 ` Linus Torvalds 2014-02-17 22:59 ` Linus Torvalds 2014-02-14 7:43 ` Jan Kara 2014-02-14 7:43 ` Jan Kara 2014-02-17 22:57 ` Linus Torvalds 2014-02-17 22:57 ` Linus Torvalds 2014-02-14 5:47 ` Nishanth Aravamudan 2014-02-14 5:47 ` Nishanth Aravamudan 2014-02-13 21:06 ` Andrew Morton 2014-02-13 21:06 ` Andrew Morton 2014-02-13 21:42 ` Nishanth Aravamudan 2014-02-13 21:42 ` Nishanth Aravamudan 2014-02-10 8:29 ` [RFC PATCH V5 RESEND] " Raghavendra K T 2014-02-10 8:29 ` Raghavendra K T
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