From: Jan Kara <jack@suse.cz> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>, David Rientjes <rientjes@google.com>, Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, 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>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Date: Fri, 14 Feb 2014 08:43:05 +0100 [thread overview] Message-ID: <20140214074305.GF5160@quack.suse.cz> (raw) In-Reply-To: <CA+55aFwH8BqyLSqyLL7g-08nOtnOrJ9vKj4ebiSqrxc5ooEjLw@mail.gmail.com> On Thu 13-02-14 16:37:53, Linus Torvalds wrote: > Is this whole thread still just for the crazy and pointless > "max_sane_readahead()"? > > Or is there some *real* reason we should care? > > Because if it really is just for max_sane_readahead(), then for the > love of God, let us just do this > > unsigned long max_sane_readahead(unsigned long nr) > { > return min(nr, 128); > } > > and bury this whole idiotic thread. max_sane_readahead() is also used for limiting amount of readahead for [fm]advice(2) WILLNEED and that is used e.g. by a dynamic linker to preload shared libraries into memory. So I'm convinced this usecase *will* notice the change - effectively we limit preloading of shared libraries to the first 512KB in the file but libraries get accessed in a rather random manner. Maybe limits for WILLNEED and for standard readahead should be different. It makes sence to me and people seem to keep forgetting that max_sane_readahead() limits also WILLNEED preloading. Honza > On Thu, Feb 13, 2014 at 4:14 PM, Nishanth Aravamudan > <nacc@linux.vnet.ibm.com> wrote: > > > > I'm working on this latter bit now. I tried to mirror ia64, but it looks > > like they have CONFIG_USER_PERCPU_NUMA_NODE_ID, which powerpc doesn't. > > It seems like CONFIG_USER_PERCPU_NUMA_NODE_ID and > > CONFIG_HAVE_MEMORYLESS_NODES should be tied together in Kconfig? > > > > I'll keep working, but would appreciate any further insight. > > > > -Nish > > -- Jan Kara <jack@suse.cz> SUSE Labs, CR
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>, David Rientjes <rientjes@google.com>, Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, 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>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Date: Fri, 14 Feb 2014 08:43:05 +0100 [thread overview] Message-ID: <20140214074305.GF5160@quack.suse.cz> (raw) In-Reply-To: <CA+55aFwH8BqyLSqyLL7g-08nOtnOrJ9vKj4ebiSqrxc5ooEjLw@mail.gmail.com> On Thu 13-02-14 16:37:53, Linus Torvalds wrote: > Is this whole thread still just for the crazy and pointless > "max_sane_readahead()"? > > Or is there some *real* reason we should care? > > Because if it really is just for max_sane_readahead(), then for the > love of God, let us just do this > > unsigned long max_sane_readahead(unsigned long nr) > { > return min(nr, 128); > } > > and bury this whole idiotic thread. max_sane_readahead() is also used for limiting amount of readahead for [fm]advice(2) WILLNEED and that is used e.g. by a dynamic linker to preload shared libraries into memory. So I'm convinced this usecase *will* notice the change - effectively we limit preloading of shared libraries to the first 512KB in the file but libraries get accessed in a rather random manner. Maybe limits for WILLNEED and for standard readahead should be different. It makes sence to me and people seem to keep forgetting that max_sane_readahead() limits also WILLNEED preloading. Honza > On Thu, Feb 13, 2014 at 4:14 PM, Nishanth Aravamudan > <nacc@linux.vnet.ibm.com> wrote: > > > > I'm working on this latter bit now. I tried to mirror ia64, but it looks > > like they have CONFIG_USER_PERCPU_NUMA_NODE_ID, which powerpc doesn't. > > It seems like CONFIG_USER_PERCPU_NUMA_NODE_ID and > > CONFIG_HAVE_MEMORYLESS_NODES should be tied together in Kconfig? > > > > I'll keep working, but would appreciate any further insight. > > > > -Nish > > -- Jan Kara <jack@suse.cz> SUSE Labs, CR -- 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:[~2014-02-14 7:43 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 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 [this message] 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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