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From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: David Gibson <david@gibson.dropbear.id.au>,
	paulus@samba.org, mpe@ellerman.id.au, benh@kernel.crashing.org
Cc: aik@ozlabs.ru, lvivier@redhat.com, thuth@redhat.com,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFCv2 9/9] pseries: Automatically resize HPT for memory hot add/remove
Date: Mon, 01 Feb 2016 14:21:46 +0530	[thread overview]
Message-ID: <56AF1CA2.30603@linux.vnet.ibm.com> (raw)
In-Reply-To: <1454045043-25545-10-git-send-email-david@gibson.dropbear.id.au>

On 01/29/2016 10:54 AM, David Gibson wrote:
>  #ifdef CONFIG_MEMORY_HOTPLUG
> +void resize_hpt_for_hotplug(unsigned long new_mem_size)
> +{
> +	unsigned target_hpt_shift;
> +
> +	if (!ppc_md.resize_hpt)
> +		return;
> +
> +	target_hpt_shift = htab_shift_for_mem_size(new_mem_size);
> +
> +	/*
> +	 * To avoid lots of HPT resizes if memory size is fluctuating
> +	 * across a boundary, we deliberately have some hysterisis


What do you mean by 'memory size is fluctuating across a boundary' ?
Through memory hotplug interface ? Why some one will do that ? I
can understand why we dont have this check in the sysfs debug path
as we would like to test any memory HPT re sizing scenario we want
in any sequence of increase or decrease we want.

Overall the RFC V2 looks pretty good. Looking forward to see the
host side of the code for this feature.

  reply	other threads:[~2016-02-01  8:52 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29  5:23 [RFCv2 0/9] PAPR hash page table resizing (guest side) David Gibson
2016-01-29  5:23 ` [RFCv2 1/9] memblock: Don't mark memblock_phys_mem_size() as __init David Gibson
2016-02-01  5:50   ` Anshuman Khandual
2016-02-08  2:46   ` Paul Mackerras
2016-01-29  5:23 ` [RFCv2 2/9] arch/powerpc: Clean up error handling for htab_remove_mapping David Gibson
2016-02-01  5:54   ` Anshuman Khandual
2016-02-08  2:48   ` Paul Mackerras
2016-01-29  5:23 ` [RFCv2 3/9] arch/powerpc: Handle removing maybe-present bolted HPTEs David Gibson
2016-02-01  5:58   ` Anshuman Khandual
2016-02-02  1:08     ` David Gibson
2016-02-02 13:49   ` Denis Kirjanov
2016-02-08  2:54   ` Paul Mackerras
2016-02-09  0:43     ` David Gibson
2016-01-29  5:23 ` [RFCv2 4/9] arch/powerpc: Clean up memory hotplug failure paths David Gibson
2016-02-01  6:29   ` Anshuman Khandual
2016-02-02 15:04   ` Nathan Fontenot
2016-02-03  4:31     ` David Gibson
2016-02-08  5:47   ` Paul Mackerras
2016-01-29  5:23 ` [RFCv2 5/9] arch/powerpc: Split hash page table sizing heuristic into a helper David Gibson
2016-02-01  7:04   ` Anshuman Khandual
2016-02-02  1:04     ` David Gibson
2016-02-04 10:56       ` Anshuman Khandual
2016-02-08  5:57         ` Paul Mackerras
2016-01-29  5:24 ` [RFCv2 6/9] pseries: Add hypercall wrappers for hash page table resizing David Gibson
2016-02-01  7:11   ` Anshuman Khandual
2016-02-02  0:58     ` David Gibson
2016-02-04 11:11       ` Anshuman Khandual
2016-02-07 22:33         ` David Gibson
2016-02-08  5:58   ` Paul Mackerras
2016-01-29  5:24 ` [RFCv2 7/9] pseries: Add support for hash " David Gibson
2016-02-01  8:31   ` Anshuman Khandual
2016-02-01 11:04     ` David Gibson
2016-02-08  5:59   ` Paul Mackerras
2016-01-29  5:24 ` [RFCv2 8/9] pseries: Advertise HPT resizing support via CAS David Gibson
2016-02-01  8:36   ` Anshuman Khandual
2016-02-08  6:00   ` Paul Mackerras
2016-01-29  5:24 ` [RFCv2 9/9] pseries: Automatically resize HPT for memory hot add/remove David Gibson
2016-02-01  8:51   ` Anshuman Khandual [this message]
2016-02-01 10:55     ` David Gibson
2016-02-08  6:01   ` Paul Mackerras
2016-02-01  5:50 ` [RFCv2 0/9] PAPR hash page table resizing (guest side) Anshuman Khandual
2016-02-02  0:57   ` David Gibson

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