From: Rik van Riel <riel@redhat.com> To: David Rientjes <rientjes@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com>, Con Kolivas <kernel@kolivas.org>, Andrew Morton <akpm@linux-foundation.org>, Randy Dunlap <rdunlap@xenotime.net>, Satoru Moriya <smoriya@redhat.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "lwoodman@redhat.com" <lwoodman@redhat.com>, Seiji Aguchi <saguchi@redhat.com>, Hugh Dickins <hughd@google.com>, "hannes@cmpxchg.org" <hannes@cmpxchg.org> Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable Date: Thu, 13 Oct 2011 17:11:59 -0400 [thread overview] Message-ID: <4E97541F.9050805@redhat.com> (raw) In-Reply-To: <alpine.DEB.2.00.1110131337580.24853@chino.kir.corp.google.com> On 10/13/2011 04:48 PM, David Rientjes wrote: > We'll never know the future and how much memory a latency-sensitive > application will require 100ms from now. The only thing that we can do is > (i) identify the latency-sensitive app, (ii) reclaim more aggressively for > them, and (iii) reclaim additional memory in preparation for another This is why I proposed a watermark solution. > burst. At some point, though, userspace needs to be responsible to not > allocate enormous amounts of memory all at once and there's room for > mitigation there too to preallocate ahead of what you actually need. Userspace cannot be responsible, for the simple reason that the allocations might be done in the kernel. Think about an mlocked realtime program handling network packets. Memory is allocated when packets come in, and when the program calls sys_send(), which causes packets to get sent. I don't see how we can make userspace responsible for kernel-side allocations. I did not propose the extra_free_kbytes patch because I like it, or out of laziness, but because I truly have not come up with a better solution. So far, neither this thread (which is unfortunate).
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com> To: David Rientjes <rientjes@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com>, Con Kolivas <kernel@kolivas.org>, Andrew Morton <akpm@linux-foundation.org>, Randy Dunlap <rdunlap@xenotime.net>, Satoru Moriya <smoriya@redhat.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "lwoodman@redhat.com" <lwoodman@redhat.com>, Seiji Aguchi <saguchi@redhat.com>, Hugh Dickins <hughd@google.com>, "hannes@cmpxchg.org" <hannes@cmpxchg.org> Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable Date: Thu, 13 Oct 2011 17:11:59 -0400 [thread overview] Message-ID: <4E97541F.9050805@redhat.com> (raw) In-Reply-To: <alpine.DEB.2.00.1110131337580.24853@chino.kir.corp.google.com> On 10/13/2011 04:48 PM, David Rientjes wrote: > We'll never know the future and how much memory a latency-sensitive > application will require 100ms from now. The only thing that we can do is > (i) identify the latency-sensitive app, (ii) reclaim more aggressively for > them, and (iii) reclaim additional memory in preparation for another This is why I proposed a watermark solution. > burst. At some point, though, userspace needs to be responsible to not > allocate enormous amounts of memory all at once and there's room for > mitigation there too to preallocate ahead of what you actually need. Userspace cannot be responsible, for the simple reason that the allocations might be done in the kernel. Think about an mlocked realtime program handling network packets. Memory is allocated when packets come in, and when the program calls sys_send(), which causes packets to get sent. I don't see how we can make userspace responsible for kernel-side allocations. I did not propose the extra_free_kbytes patch because I like it, or out of laziness, but because I truly have not come up with a better solution. So far, neither this thread (which is unfortunate). -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-10-13 21:12 UTC|newest] Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-09-01 14:52 [PATCH -mm] add extra free kbytes tunable Rik van Riel 2011-09-01 14:52 ` Rik van Riel 2011-09-01 17:06 ` Randy Dunlap 2011-09-01 17:06 ` Randy Dunlap 2011-09-01 19:26 ` [PATCH -v2 " Rik van Riel 2011-09-01 19:26 ` Rik van Riel 2011-09-01 21:58 ` Andrew Morton 2011-09-01 21:58 ` Andrew Morton 2011-09-01 22:08 ` David Rientjes 2011-09-01 22:08 ` David Rientjes 2011-09-01 22:16 ` Andrew Morton 2011-09-01 22:16 ` Andrew Morton 2011-09-02 16:31 ` Satoru Moriya 2011-09-02 16:31 ` Satoru Moriya 2011-10-13 7:33 ` Minchan Kim 2011-10-13 7:33 ` Minchan Kim 2011-10-13 8:09 ` KAMEZAWA Hiroyuki 2011-10-13 8:09 ` KAMEZAWA Hiroyuki [not found] ` <E1FA588BC672D846BDBB452FCA1E308C2389B4@USINDEVS02.corp.hds.com> 2011-09-15 3:33 ` Satoru Moriya 2011-09-15 3:33 ` Satoru Moriya 2011-09-01 22:09 ` Andrew Morton 2011-09-01 22:09 ` Andrew Morton 2011-09-02 16:26 ` [PATCH -mm] fixes & cleanups for "add extra free kbytes tunable" Rik van Riel 2011-09-02 16:26 ` Rik van Riel 2011-09-30 21:43 ` [PATCH -v2 -mm] add extra free kbytes tunable Johannes Weiner 2011-09-30 21:43 ` Johannes Weiner 2011-10-08 3:08 ` David Rientjes 2011-10-08 3:08 ` David Rientjes 2011-10-10 22:37 ` Andrew Morton 2011-10-10 22:37 ` Andrew Morton 2011-10-11 19:32 ` Satoru Moriya 2011-10-11 19:32 ` Satoru Moriya 2011-10-11 19:54 ` Andrew Morton 2011-10-11 19:54 ` Andrew Morton 2011-10-11 20:23 ` Satoru Moriya 2011-10-11 20:23 ` Satoru Moriya 2011-10-11 20:54 ` Andrew Morton 2011-10-11 20:54 ` Andrew Morton 2011-10-12 13:09 ` Rik van Riel 2011-10-12 13:09 ` Rik van Riel 2011-10-12 19:20 ` Andrew Morton 2011-10-12 19:20 ` Andrew Morton 2011-10-12 19:58 ` Rik van Riel 2011-10-12 19:58 ` Rik van Riel 2011-10-12 20:26 ` David Rientjes 2011-10-12 20:26 ` David Rientjes 2011-10-21 23:48 ` Satoru Moriya 2011-10-21 23:48 ` Satoru Moriya 2011-10-23 21:22 ` David Rientjes 2011-10-23 21:22 ` David Rientjes 2011-10-25 2:04 ` Satoru Moriya 2011-10-25 2:04 ` Satoru Moriya 2011-10-25 21:50 ` David Rientjes 2011-10-25 21:50 ` David Rientjes 2011-10-26 18:59 ` Satoru Moriya 2011-10-26 18:59 ` Satoru Moriya 2011-10-12 21:08 ` Satoru Moriya 2011-10-12 21:08 ` Satoru Moriya 2011-10-12 22:41 ` David Rientjes 2011-10-12 22:41 ` David Rientjes 2011-10-12 23:52 ` Satoru Moriya 2011-10-12 23:52 ` Satoru Moriya 2011-10-13 0:01 ` David Rientjes 2011-10-13 0:01 ` David Rientjes 2011-10-13 5:35 ` KAMEZAWA Hiroyuki 2011-10-13 5:35 ` KAMEZAWA Hiroyuki 2011-10-13 20:55 ` David Rientjes 2011-10-13 20:55 ` David Rientjes 2011-10-14 22:16 ` Satoru Moriya 2011-10-14 22:16 ` Satoru Moriya 2011-10-14 22:46 ` David Rientjes 2011-10-14 22:46 ` David Rientjes 2011-10-14 5:32 ` Satoru Moriya 2011-10-14 5:32 ` Satoru Moriya 2011-10-14 5:06 ` Satoru Moriya 2011-10-14 5:06 ` Satoru Moriya 2011-10-11 23:22 ` David Rientjes 2011-10-11 23:22 ` David Rientjes 2011-10-13 16:54 ` Satoru Moriya 2011-10-13 16:54 ` Satoru Moriya 2011-10-13 20:48 ` David Rientjes 2011-10-13 20:48 ` David Rientjes 2011-10-13 21:11 ` Rik van Riel [this message] 2011-10-13 21:11 ` Rik van Riel 2011-10-13 22:02 ` David Rientjes 2011-10-13 22:02 ` David Rientjes 2011-10-11 19:20 ` Satoru Moriya 2011-10-11 19:20 ` Satoru Moriya 2011-10-11 21:04 ` David Rientjes 2011-10-11 21:04 ` David Rientjes 2011-10-12 13:13 ` Rik van Riel 2011-10-12 13:13 ` Rik van Riel 2011-10-12 20:21 ` David Rientjes 2011-10-12 20:21 ` David Rientjes 2011-10-13 4:13 ` Rik van Riel 2011-10-13 4:13 ` Rik van Riel 2011-10-13 5:22 ` David Rientjes 2011-10-13 5:22 ` David Rientjes 2011-10-22 0:11 ` Satoru Moriya 2011-10-22 0:11 ` Satoru Moriya 2011-09-09 23:01 Satoru Moriya 2011-09-09 23:01 ` Satoru Moriya
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