RE: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled RE: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:

From: KY Srinivasan
Date: Thu Mar 06 2014 - 05:25:38 EST

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In reply to: Victor Miasnikov: "Re: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled RE: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:"
Next in thread: Victor Miasnikov: "Re: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled RE: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:"
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Victor,

I will try to get my in-context onlining patches accepted upstream.

K. Y

> -----Original Message-----
> From: Victor Miasnikov [mailto:vvm@xxxxxx]
> Sent: Thursday, March 6, 2014 3:38 PM
> To: linux-kernel@xxxxxxxxxxxxxxx; Brian Wong
> Cc: Abhishek Gupta (LIS); KY Srinivasan
> Subject: Re: Linux does not use more than the startup RAM under Hyper-V
> with dynamic memory enabled RE: [PATCH 2/2] Drivers: hv: balloon: Online
> the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:
>
> Hi!
>
> Short:
>
> Question to Linux kernel team:
>
> may be patch
>
> >>> [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in
> context"
>
> can solve problems with dynamic memory hot add in Hyper-V VMs with Linux
> OS ?
>
>
>
> Full:
>
> BW>> .., if I set the startup memory to 512 MB, and enable dynamic
> BW>> memory with a minimum of 512 MB and a maximum of 8192 MB, the
> BW>> system will never allocate than 512 MB of physical memory
>
> BW>>
> BW>> Have I encountered a bug in the Hyper-V balloon driver?
> BW>>
>
> Unfortunately, It's long story . . . :-(
>
> a)
>
> I already ( on January 09, 2014 2:18 PM ) write about problems with "Online
> the hot-added memory" in "user space" see P.P.S.
>
> b)
>
> See
>
> Bug 979257 -[Hyper-V][RHEL6.5][RFE]in-kernel online support for memory
> hot-add
> https://bugzilla.redhat.com/show_bug.cgi?id=979257
>
> ( Info from this topic may be interessant not only for RedHat users )
>
>
> b2)
>
> Detail about pathes related problem "Online the hot-added memory" in
> "user space" :
>
> >>> [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in
> context"
> >>>
> >>>
> >>> === 0001-Drivers-base-memory-Export-functionality-for-in-kern.patch
> >>> . . .
> >>> +/*
> >>> + * Given the start pfn of a memory block; bring the memory
> >>> + * block online. This API would be useful for drivers that may
> >>> + * want to bring "online" the memory that has been hot-added.
> >>> + */
> >>> +
> >>> +int online_memory_block(unsigned long start_pfn) { struct
> >>> +mem_section *cur_section; struct memory_block
> *cur_memory_block;
> >>>
> >>> . . .
> >>> ===
> >>>
> >>>
> >>> ==
> >>> . . .
> >>> == 0002-Drivers-hv-balloon-Online-the-hot-added-memory-in-co.patch
> >>> . . .
> >>> /*
> >>> - * Wait for the memory block to be onlined.
> >>> - * Since the hot add has succeeded, it is ok to
> >>> - * proceed even if the pages in the hot added region
> >>> - * have not been "onlined" within the allowed time.
> >>> + * Before proceeding to hot add the next segment,
> >>> + * online the segment that has been hot added.
> >>> */
> >>> - wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
> >>> + online_memory_block(start_pfn);
> >>>
> >>> }
>
>
>
>
> c)
>
> Before apply patches ( see in P.S. about native udev-script) we are need use
> one of this methods:
>
> http://social.technet.microsoft.com/Forums/en-US/8e1994b9-9ca1-4411-
> ad8e-25e6b1ee28e1/dynamic-memory-on-linux-
> vm?forum=linuxintegrationservices
>
>
>
> c1)
>
> "/bin/cp method" by Nikolay Pushkarev :
>
> Following udev rule works slightly faster for me (assuming that memory0
> bank always in online state):
>
> SUBSYSTEM=="memory", ACTION=="add",
> DEVPATH=="/devices/system/memory/memory[1-9]*",
> RUN+="/bin/cp /sys$devpath/../memory0/state /sys$devpath/state"}}
>
> ( VVM : of course all need be place in one line, 2 line in this msg. -- only for
> good visual formating reasons )
>
>
> c2)
>
> udev rule using "putarg" by Nikolay Pushkarev :
>
>
> Even "/bin/cp method" udev rule work time to time not as need :-(
>
>
> As a result, Nikolay Pushkarev write a program putarg.c, that is even faster
> than "/bin/cp method" :
>
> ==
> #include <stdio.h>
> #include <fcntl.h>
> #include <sys/ioctl.h>
> #include <string.h>
> int main(int argc, char** argv) {
> int i, fd;
> if (argc < 2) return 0;
> if ((fd = open(argv[1], O_RDWR)) < 0) return 1;
> for (i = 2; i < argc; i++) {
> if (write(fd, argv[i], strlen(argv[i])) < 0) {
> close(fd);
> return i;
> }
> }
> close(fd);
> return 0;
> }
> ==
>
> The first argument - the name of the output file , and argument number 2 (
> and all subsequent ( if exist ) ) - are text that are wiil be written in output file.
>
>
> Compile source code to executable file by run command:
> gcc -o putarg -s putarg.c
>
> The resulting binary need be placed an accessible location , such as /usr/bin,
> or wherever you want.
>
>
> Now udev rule using "putarg" can be written as :
>
> SUBSYSTEM=="memory", ACTION=="add", RUN+="/usr/bin/putarg
> /sys$devpath/state online"
>
>
> This complex solutions ( compiled file and udev-rule ) works exceptionally
> fast.
>
>
>
>
>
> Best regards, Victor Miasnikov
> Blog: http://vvm.blog.tut.by/
>
> P.S.
>
> Nikolay Pushkarev about standart udev-script :
>
> {{
>
> Strange, that the native udev-script
>
> SUBSYSTEM=="memory", ACTION=="add", ATTR{state}="online"
>
>
> triggered somehow through time ( VVM: very often not work as need )
>
>
> }}
>
>
>
> P.P.S.
>
> ----- Original Message -----
> From: "Victor Miasnikov"
> To: "Dan Carpenter"; "K. Y. Srinivasan" ; <linux-kernel@xxxxxxxxxxxxxxx>
> Cc: "Greg KH" ; <devel@xxxxxxxxxxxxxxxxxxxxxx>; <olaf (at) aepfle.de>;
> ""Andy Whitcroft"" <zzzzzzzzzzzz (at) canonical.com>; <jasowang (at)
> redhat.com>
> Sent: Thursday, January 09, 2014 2:18 PM
> Subject: RE: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory
> "in context" Re: [PATCH 1/1] Drivers: hv:
> Implement the file copy service
>
>
> Hi!
>
> > Is there no way we could implement file copying in user space?
>
>
> For "file copy service" "user space" may be pretty good
>
> But I ( and other Hyper-V sysadmin) see non-Ok ( in "political correct"
> terminalogy) results with "hv: balloon: Online
> the hot-added memory" in "user space"
>
>
> ==
> [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context"
> ==
>
>
> What news? Roadmap?
>
>
> Best regards, Victor Miasnikov
> Blog: http://vvm.blog.tut.by/
>
>
>
>
> P.P.S.
>
> ----- Original Message -----
> From: "Brian Wong"
> To: <linux-kernel@xxxxxxxxxxxxxxx>
> Sent: Thursday, March 06, 2014 9:24 AM
> Subject: Re: Linux does not use more than the startup RAM under Hyper-V
> with dynamic memory enabled
>
>
> On 3/6/2014 1:20 AM, Brian Wong wrote:
>
> . . .
>
> > The kernel is built with the full set of Hyper-V drivers, including the
> > key "Microsoft Hyper-V Balloon Driver" as well as memory hot-add and
> > hot-remove functionality. This is happening with both the Gentoo-patched
> > 3.10.32 kernel and the vanilla 3.12.5 kernel. The host machine has a
> > total of 24 GB of memory.
> >
> > For now, I am working around the issue by starting the VM with the
> > startup memory set to the maximum and letting Hyper-V take the usused
> > memory back when it is not in use. The VM will then get the extra memory
> > when it needs it.
> >
> > Have I encountered a bug in the Hyper-V balloon driver?
> >
>
> Just a correction: the vanilla kernel version is 3.13.5, not 3.12.5.
> Sorry for any confusion.
>
> --
> Brian Wong
> http://www.fierydragonlord.com
> --
>
>
>
> ----- Original Message -----
> From: "Brian Wong"
> To: <linux-kernel@xxxxxxxxxxxxxxx>
> Sent: Thursday, March 06, 2014 9:20 AM
> Subject: Linux does not use more than the startup RAM under Hyper-V with
> dynamic memory enabled
>
> I'm new to LKML, so please don't be too hard on me :)
>
> I'm running Gentoo Linux under Microsoft Client Hyper-V on Windows 8.1
> Pro, and I've noticed some odd behavior with respect to dynamic memory
> (aka memory ballooning). The system will never use more than the startup
> memory defined in the virtual machine's settings.
>
> ( VVM: typewriting error viRtual fixed by me, for best search in future )
>
> For example, if I set the startup memory to 512 MB, and enable dynamic
> memory with a minimum of 512 MB and a maximum of 8192 MB, the system
> will never allocate than 512 MB of physical memory, despite Hyper-V
> assigning more memory to the VM and the added memory being visible in
> the output of "free" and "htop". Attempting to use more memory causes
> the system to start paging to swap, rather than actually allocating the
> memory above the startup memory assigned to the VM.
>
> The kernel is built with the full set of Hyper-V drivers, including the
> key "Microsoft Hyper-V Balloon Driver" as well as memory hot-add and
> hot-remove functionality. This is happening with both the Gentoo-patched
> 3.10.32 kernel and the vanilla 3.12.5 kernel. The host machine has a
> total of 24 GB of memory.
>
> (
> Brian Wong wrote On 3/6/2014 1:20 AM:
> Just a correction: the vanilla kernel version is 3.13.5, not 3.12.5. )
> )
>
> For now, I am working around the issue by starting the VM with the
> startup memory set to the maximum and letting Hyper-V take the usused
> memory back when it is not in use. The VM will then get the extra memory
> when it needs it.
>
> Have I encountered a bug in the Hyper-V balloon driver?
>
> --
> Brian Wong
> http://www.fierydragonlord.com
> --
>
>
>

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