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From: Nadia Derbey <>
To: Yasunori Goto <>
Subject: Re: [RFC PATCH 4/4] [RESEND] Recomputing msgmni on memory add / remove
Date: Tue, 15 Jan 2008 10:03:16 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Yasunori Goto wrote:
> Hello Nadia-san.
>>@@ -118,6 +122,10 @@ struct ipc_namespace {
>> 	size_t		shm_ctlall;
>> 	int		shm_ctlmni;
>> 	int		shm_tot;
>>+	struct notifier_block ipc_memory_hotplug;
>> };
> I'm sorry, but I don't see why each ipc namespace must have each callbacks
> of memory hotplug.
> I prefer only one callback for each subsystem, not for each namespace.
> In addition, the recompute_msgmni() calculation looks very similar for
> all ipc namespace.
> Or do you wish each ipc namespace have different callback for the future?

Actually, this is what I wanted to do at the very beginning: have a 
single callback that would recompute the msgmni for each ipc namespace. 
But the issue here is that the namespaces are not linked to each other, 
so I had no simple way to go through all the namespaces.
I solved the issue by having a callback for any single ipc namespace and 
make it recompute the msgmni value for itslef.

> BTW, have you ever tested this patch? If you don't have any test environment
> for memory hotplug code, then I'll check it. :-)

Well, I tested it but not in "real configuration": what I did is that I 
changed the status by hand under sysfs to offline. I also changed 
remove_memory() in mm/memory_hotplug.c in the following way (instead of 
returninf EINVAL):
1) decrease the total_ram pages
2) call memory_notify(MEM_OFFLINE, NULL)

and checked that the msgmni was recomputed.

But sure, if you are candidate to test it, that would be great!


  reply	other threads:[~2008-01-15  9:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-14 15:54 [RFC PATCH 0/4] [RESEND] Change default MSGMNI tunable to scale with lowmem Nadia.Derbey
2008-01-14 15:54 ` [RFC PATCH 1/4] [RESEND] Scaling msgmni to the amount of lowmem Nadia.Derbey
2008-01-14 15:54 ` [RFC PATCH 2/4] [RESEND] Scaling msgmni to the number of ipc namespaces Nadia.Derbey
2008-01-14 15:54 ` [RFC PATCH 3/4] [RESEND] Defining the slab_memory_callback priority as a constant Nadia.Derbey
2008-01-14 15:54 ` [RFC PATCH 4/4] [RESEND] Recomputing msgmni on memory add / remove Nadia.Derbey
2008-01-15  8:07   ` Yasunori Goto
2008-01-15  9:03     ` Nadia Derbey [this message]
2008-01-15  9:40       ` Yasunori Goto
2008-01-15 10:16         ` Nadia Derbey
2008-01-15  9:06 ` [RFC PATCH 0/4] [RESEND] Change default MSGMNI tunable to scale with lowmem Nadia Derbey
2008-01-15  9:21   ` Matt Helsley

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