From: Eric Blake <eblake@redhat.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [RFC PATCH qemu] qapi: Add query-memory-checksum
Date: Wed, 21 Aug 2019 20:33:04 -0500 [thread overview]
Message-ID: <b9098689-a8cb-0c68-0065-f9362cdcb32d@redhat.com> (raw)
In-Reply-To: <20190822011620.106337-1-aik@ozlabs.ru>
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On 8/21/19 8:16 PM, Alexey Kardashevskiy wrote:
> This returns MD5 checksum of all RAM blocks for migration debugging
> as this is way faster than saving the entire RAM to a file and checking
> that.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>
>
> I am actually wondering if there is an easier way of getting these
> checksums and I just do not see it, it cannot be that we fixed all
> memory migration bugs :)
I'm not sure whether the command itself makes sense, but for the interface:
> +++ b/qapi/misc.json
> @@ -1194,6 +1194,33 @@
> ##
> { 'command': 'query-memory-size-summary', 'returns': 'MemoryInfo' }
>
> +##
> +# @MemoryChecksum:
> +#
> +# A string with MD5 checksum of all RAMBlocks.
> +#
> +# @checksum: the checksum.
> +#
> +# Since: 3.2.0
This should be 4.2, not 3.2.
> +##
> +{ 'struct': 'MemoryChecksum',
> + 'data' : { 'checksum': 'str' } }
> +
> +##
> +# @query-memory-checksum:
> +#
> +# Return the MD5 checksum of all RAMBlocks.
> +#
> +# Example:
> +#
> +# -> { "execute": "query-memory-checksum" }
> +# <- { "return": { "checksum": "a0880304994f64cb2edad77b9a1cd58f" } }
> +#
> +# Since: 3.2.0
and again
> +##
> +{ 'command': 'query-memory-checksum',
> + 'returns': 'MemoryChecksum' }
> +
>
> +++ b/exec.c
> @@ -2050,6 +2050,22 @@ void *qemu_ram_get_host_addr(RAMBlock *rb)
> return rb->host;
> }
>
> +gchar *qemu_ram_chksum(void)
gchar is a pointless glib type. Use 'char' instead.
> +{
> + struct RAMBlock *rb;
> + GChecksum *chksum = g_checksum_new(G_CHECKSUM_MD5);
> + gchar *ret;
> +
> + RAMBLOCK_FOREACH(rb) {
> + g_checksum_update(chksum, qemu_ram_get_host_addr(rb),
> + qemu_ram_get_used_length(rb));
> + }
> + ret = g_strdup(g_checksum_get_string(chksum));
> + g_checksum_free(chksum);
> +
> + return ret;
> +}
How long does this take to run? Is it something where you really want
to block the guest while chewing over the guest's entire memory?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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next prev parent reply other threads:[~2019-08-22 1:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 1:16 [Qemu-devel] [RFC PATCH qemu] qapi: Add query-memory-checksum Alexey Kardashevskiy
2019-08-22 1:33 ` Eric Blake [this message]
2019-08-22 3:20 ` Alexey Kardashevskiy
2019-08-22 14:16 ` Markus Armbruster
2019-08-22 14:49 ` Daniel P. Berrangé
2019-08-23 5:49 ` Markus Armbruster
2019-08-23 9:23 ` Daniel P. Berrangé
2019-08-23 11:41 ` Markus Armbruster
2019-08-26 4:28 ` Alexey Kardashevskiy
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