From: Arun KS <arunks@codeaurora.org>
To: Juergen Gross <jgross@suse.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com,
sthemmin@microsoft.com, boris.ostrovsky@oracle.com,
akpm@linux-foundation.org, dan.j.williams@intel.com,
mhocko@suse.com, vbabka@suse.cz, iamjoonsoo.kim@lge.com,
gregkh@linuxfoundation.org, osalvador@suse.de, malat@debian.org,
kirill.shutemov@linux.intel.com, jrdr.linux@gmail.com,
yasu.isimatu@gmail.com, mgorman@techsingularity.net,
aaron.lu@intel.com, devel@linuxdriverproject.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
xen-devel@lists.xenproject.org, vatsa@codeaurora.org,
vinmenon@codeaurora.org, getarunks@gmail.com
Subject: Re: [PATCH v3] memory_hotplug: Free pages as higher order
Date: Thu, 27 Sep 2018 13:41:45 +0530 [thread overview]
Message-ID: <21949851c3b2c82853588101f39f1207@codeaurora.org> (raw)
In-Reply-To: <36488c0e-6bae-e277-2cdb-32d0dcc40065@suse.com>
On 2018-09-27 12:41, Juergen Gross wrote:
> On 27/09/18 08:58, Arun KS wrote:
>> When free pages are done with higher order, time spend on
>> coalescing pages by buddy allocator can be reduced. With
>> section size of 256MB, hot add latency of a single section
>> shows improvement from 50-60 ms to less than 1 ms, hence
>> improving the hot add latency by 60%.
>>
>> Modify external providers of online callback to align with
>> the change.
>>
>> Signed-off-by: Arun KS <arunks@codeaurora.org>
>> ---
>> Changes since v2:
>> reuse code from __free_pages_boot_core()
>>
>> Changes since v1:
>> - Removed prefetch()
>>
>> Changes since RFC:
>> - Rebase.
>> - As suggested by Michal Hocko remove pages_per_block.
>> - Modifed external providers of online_page_callback.
>>
>> v2: https://lore.kernel.org/patchwork/patch/991363/
>> v1: https://lore.kernel.org/patchwork/patch/989445/
>> RFC: https://lore.kernel.org/patchwork/patch/984754/
>>
>> ---
>> drivers/hv/hv_balloon.c | 6 ++++--
>> drivers/xen/balloon.c | 18 ++++++++++++++---
>> include/linux/memory_hotplug.h | 2 +-
>> mm/internal.h | 1 +
>> mm/memory_hotplug.c | 44
>> ++++++++++++++++++++++++++++++------------
>> mm/page_alloc.c | 2 +-
>> 6 files changed, 54 insertions(+), 19 deletions(-)
>>
>
> ...
>
>> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
>> index e12bb25..010cf4d 100644
>> --- a/drivers/xen/balloon.c
>> +++ b/drivers/xen/balloon.c
>> @@ -390,8 +390,8 @@ static enum bp_state
>> reserve_additional_memory(void)
>>
>> /*
>> * add_memory_resource() will call online_pages() which in its turn
>> - * will call xen_online_page() callback causing deadlock if we don't
>> - * release balloon_mutex here. Unlocking here is safe because the
>> + * will call xen_bring_pgs_online() callback causing deadlock if we
>> + * don't release balloon_mutex here. Unlocking here is safe because
>> the
>> * callers drop the mutex before trying again.
>> */
>> mutex_unlock(&balloon_mutex);
>> @@ -422,6 +422,18 @@ static void xen_online_page(struct page *page)
>> mutex_unlock(&balloon_mutex);
>> }
>>
>> +static int xen_bring_pgs_online(struct page *pg, unsigned int order)
>> +{
>> + unsigned long i, size = (1 << order);
>> + unsigned long start_pfn = page_to_pfn(pg);
>> +
>> + pr_debug("Online %lu pages starting at pfn 0x%lx\n", size,
>> start_pfn);
>> + for (i = 0; i < size; i++)
>> + xen_online_page(pfn_to_page(start_pfn + i));
>
Hi,
> xen_online_page() isn't very complex and this is the only user.
>
> Why don't you move its body in here and drop the extra function?
> And now you can execute the loop with balloon_mutex held instead of
> taking and releasing it in each iteration of the loop.
Point taken. Will incorporate them.
Regards,
Arun
>
>
> Juergen
prev parent reply other threads:[~2018-09-27 8:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 6:58 [PATCH v3] memory_hotplug: Free pages as higher order Arun KS
2018-09-27 7:09 ` Oscar Salvador
2018-09-27 8:09 ` Arun KS
2018-09-27 7:11 ` Juergen Gross
2018-09-27 8:11 ` Arun KS [this message]
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