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Re: [xen-devel][vNUMA v2][PATCH 1/8] Config options

Dulloor wrote:
On Tue, Aug 3, 2010 at 5:40 AM, Andre Przywara <andre.przywara@xxxxxxx> wrote:
Dulloor wrote:
Implement the following config options :

strategy = "str", where str is confine/stripe/split/auto
vnodes = <num-nodes>
stripesz = <size-in-pages>
As Ian already said, I'd also prefer NUMA related names instead of
the generic "strategy". Also "vnodes" may be a bit misleading, what about
That's right. How about "numa_strategy", "numa_vnodes", and "numa_stripesz" ?
The numa_vnodes looks quite cumbersome and isn't very intuitive in understanding. I'd prefer numa_guestnodes (although this is a bit long) cause it is clear in what it means. But I can also live with numa_vnodes if this is put in the example config file together with an appropriate comment.

+typedef struct xc_domain_numa_config
+    uint32_t strategy;      /* By default, DONTCARE (for now) */
+    uint32_t nr_nodes;      /* For SPLIT/STRIPE */
+    uint32_t stripe_size;   /* For STRIPE only */
Are 32 bit here sufficient? Although for the stripe size probably 4GB
are more than needed, I'd prefer to use 64bit (or long) for each
memory-related variable.
Here, stripe_size is in 4K pages, so effectively we have 44 bits,
which should suffice.
But, for consistency, I will change that to 64-bit.
Thanks. I think we all should have learned from the "640 KB is enough" story ;-)

+} xc_domain_numa_config_t;
+++ b/tools/libxl/xl_cmdimpl.c
+static uint32_t numa_str_to_val(const char *str)
+    if (!strcasecmp(str, "AUTO"))
+        return XC_DOM_NUMA_AUTO;
+    if (!strcasecmp(str, "CONFINE"))
+        return XC_DOM_NUMA_CONFINE;
+    if (!strcasecmp(str, "SPLIT"))
+        return XC_DOM_NUMA_SPLIT;
+    if (!strcasecmp(str, "STRIPE"))
+        return XC_DOM_NUMA_STRIPE;
+    return XC_DOM_NUMA_NONE;
Shouldn't the function return something like "unknown" here?
This would allow to detect typos in the config file.
I  was thinking that if someone misconfigures (or for typos), we fall back
to the current case. But, it makes sense not to do that. Will change this.
I was already seeing the mails on xen-devel asking why numa_strategy=strip doesn't make a difference ;-) If we have only a few possible strategies, we should fail on illegal ones. That would also make later extension easier to use, as they fail on older setups and the user gets a hint on this.


Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12

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