From: Wei Yang <richard.weiyang@linux.alibaba.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org,
linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org,
linux-s390@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Michal Hocko <mhocko@suse.com>,
"Michael S . Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>, Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH v4 6/8] virtio-mem: try to merge system ram resources
Date: Wed, 16 Sep 2020 20:52:14 +0800 [thread overview]
Message-ID: <20200916125214.GB48039@L-31X9LVDL-1304.local> (raw)
In-Reply-To: <20200911103459.10306-7-david@redhat.com>
On Fri, Sep 11, 2020 at 12:34:57PM +0200, David Hildenbrand wrote:
>virtio-mem adds memory in memory block granularity, to be able to
>remove it in the same granularity again later, and to grow slowly on
>demand. This, however, results in quite a lot of resources when
>adding a lot of memory. Resources are effectively stored in a list-based
>tree. Having a lot of resources not only wastes memory, it also makes
>traversing that tree more expensive, and makes /proc/iomem explode in
>size (e.g., requiring kexec-tools to manually merge resources later
>when e.g., trying to create a kdump header).
>
>Before this patch, we get (/proc/iomem) when hotplugging 2G via virtio-mem
>on x86-64:
> [...]
> 100000000-13fffffff : System RAM
> 140000000-33fffffff : virtio0
> 140000000-147ffffff : System RAM (virtio_mem)
> 148000000-14fffffff : System RAM (virtio_mem)
> 150000000-157ffffff : System RAM (virtio_mem)
> 158000000-15fffffff : System RAM (virtio_mem)
> 160000000-167ffffff : System RAM (virtio_mem)
> 168000000-16fffffff : System RAM (virtio_mem)
> 170000000-177ffffff : System RAM (virtio_mem)
> 178000000-17fffffff : System RAM (virtio_mem)
> 180000000-187ffffff : System RAM (virtio_mem)
> 188000000-18fffffff : System RAM (virtio_mem)
> 190000000-197ffffff : System RAM (virtio_mem)
> 198000000-19fffffff : System RAM (virtio_mem)
> 1a0000000-1a7ffffff : System RAM (virtio_mem)
> 1a8000000-1afffffff : System RAM (virtio_mem)
> 1b0000000-1b7ffffff : System RAM (virtio_mem)
> 1b8000000-1bfffffff : System RAM (virtio_mem)
> 3280000000-32ffffffff : PCI Bus 0000:00
>
>With this patch, we get (/proc/iomem):
> [...]
> fffc0000-ffffffff : Reserved
> 100000000-13fffffff : System RAM
> 140000000-33fffffff : virtio0
> 140000000-1bfffffff : System RAM (virtio_mem)
> 3280000000-32ffffffff : PCI Bus 0000:00
>
>Of course, with more hotplugged memory, it gets worse. When unplugging
>memory blocks again, try_remove_memory() (via
>offline_and_remove_memory()) will properly split the resource up again.
>
>Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Cc: Michal Hocko <mhocko@suse.com>
>Cc: Dan Williams <dan.j.williams@intel.com>
>Cc: Michael S. Tsirkin <mst@redhat.com>
>Cc: Jason Wang <jasowang@redhat.com>
>Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
>Cc: Baoquan He <bhe@redhat.com>
>Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
>---
> drivers/virtio/virtio_mem.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
>index ed99e43354010..ba4de598f6636 100644
>--- a/drivers/virtio/virtio_mem.c
>+++ b/drivers/virtio/virtio_mem.c
>@@ -424,7 +424,8 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
>
> dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
> return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
>- vm->resource_name, MHP_NONE);
>+ vm->resource_name,
>+ MEMHP_MERGE_RESOURCE);
> }
>
> /*
>--
>2.26.2
--
Wei Yang
Help you, Help me
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next prev parent reply other threads:[~2020-09-16 12:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 10:34 [PATCH v4 0/8] selective merging of system ram resources David Hildenbrand
2020-09-11 10:34 ` [PATCH v4 1/8] kernel/resource: make release_mem_region_adjustable() never fail David Hildenbrand
2020-09-22 6:07 ` [PATCH] kernel/resource: Fix use of ternary condition in release_mem_region_adjustable Nathan Chancellor
2020-09-22 6:22 ` David Hildenbrand
2020-10-09 9:24 ` Wei Yang
2020-09-11 10:34 ` [PATCH v4 2/8] kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED David Hildenbrand
2020-09-11 10:34 ` [PATCH v4 3/8] mm/memory_hotplug: guard more declarations by CONFIG_MEMORY_HOTPLUG David Hildenbrand
2020-09-11 10:34 ` [PATCH v4 4/8] mm/memory_hotplug: prepare passing flags to add_memory() and friends David Hildenbrand
2020-09-11 10:34 ` [PATCH v4 5/8] mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System RAM resources David Hildenbrand
2020-09-15 2:43 ` Wei Yang
2020-09-15 7:25 ` David Hildenbrand
2020-09-16 12:51 ` Wei Yang
2020-09-11 10:34 ` [PATCH v4 6/8] virtio-mem: try to merge system ram resources David Hildenbrand
2020-09-16 12:52 ` Wei Yang [this message]
2020-09-11 10:34 ` [PATCH v4 7/8] xen/balloon: " David Hildenbrand
2020-09-16 12:52 ` Wei Yang
2020-09-11 10:34 ` [PATCH v4 8/8] hv_balloon: " David Hildenbrand
2020-09-16 12:52 ` Wei Yang
2020-09-16 7:30 ` [PATCH] kernel/resource: make iomem_resource implicit in release_mem_region_adjustable() David Hildenbrand
2020-09-16 10:02 ` Wei Yang
2020-09-16 10:03 ` David Hildenbrand
2020-09-16 12:10 ` Wei Yang
2020-09-16 12:16 ` David Hildenbrand
2020-09-16 12:40 ` Wei Yang
2020-09-17 8:38 ` Pankaj Gupta
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