From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCHv3 3/4] xen: use ticket locks for spin locks
Date: Tue, 28 Apr 2015 16:56:20 +0100
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To: Jan Beulich <JBeulich@suse.com>, David Vrabel <david.vrabel@citrix.com>
Cc: Keir Fraser <keir@xen.org>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Tim Deegan <tim@xen.org>, Jennifer Herbert <jennifer.herbert@citrix.com>, xen-devel@lists.xenproject.org
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On 23/04/15 12:58, Jan Beulich wrote:
>
>> +typedef union {
>> +    u32 head_tail;
>> +    struct {
>> +        u16 head;
>> +        u16 tail;
>> +    };
>> +} spinlock_tickets_t;
>> +
>>  typedef struct spinlock {
>> -    raw_spinlock_t raw;
>> +    spinlock_tickets_t tickets;
> 
> At least for x86 this means a growth of this and hence various
> other structures - did you examine the effects thereof? Of
> course otoh getting the lock size uniform across architectures
> is a good thing.

I've not looked.

Are there any structures whose size you're particularly concerned about?

David