Re: [PATCH v3 5/9] Implement public API for virDomainSetIOThreads

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On 03/04/2015 01:00 PM, Ján Tomko wrote:
> On Tue, Feb 17, 2015 at 04:03:54PM -0500, John Ferlan wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1135491
>>
>> Add the libvirt API infrastructure to support setting IOThread data.
>> For now this is the pinned CPU information, but eventually will also
>> support hot plug add/del
>>
>> The API will support the LIVE, CONFIG, or CURRENT flags.  If the
>> VIR_DOMAIN_IOTHREADS_PIN flag is not provided, it's left up to the
>> hypervisor to handle, but when not provided the cpumap/maplen arguments
>> are not checked.
>>
>> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
>> ---
>>  include/libvirt/libvirt-domain.h | 16 ++++++++++
>>  src/driver-hypervisor.h          |  8 +++++
>>  src/libvirt-domain.c             | 69 ++++++++++++++++++++++++++++++++++++++++
>>  src/libvirt_public.syms          |  1 +
>>  4 files changed, 94 insertions(+)
>>
>> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
>> index 9dcc424..e07db16 100644
>> --- a/include/libvirt/libvirt-domain.h
>> +++ b/include/libvirt/libvirt-domain.h
>> @@ -1582,11 +1582,27 @@ struct _virDomainIOThreadsInfo {
>>      char **resources;                  /* array of resources using IOThread */
>>  };
>>  
>> +/* Flags for controlling virtual IOThread pinning.  */
>> +typedef enum {
>> +    /* See virDomainModificationImpact for these flags.  */
>> +    VIR_DOMAIN_IOTHREADS_CURRENT = VIR_DOMAIN_AFFECT_CURRENT,
>> +    VIR_DOMAIN_IOTHREADS_LIVE    = VIR_DOMAIN_AFFECT_LIVE,
>> +    VIR_DOMAIN_IOTHREADS_CONFIG  = VIR_DOMAIN_AFFECT_CONFIG,
>> +
>> +    /* Additionally, these flags may be bitwise-OR'd in.  */
>> +    VIR_DOMAIN_IOTHREADS_PIN = (1 << 2), /* thread_id to pin using cpumap */
>> +} virDomainIOThreadsFlags;
>> +
>>  void                 virDomainIOThreadsInfoFree(virDomainIOThreadsInfoPtr info);
>>  
>>  int                  virDomainGetIOThreadsInfo(virDomainPtr domain,
>>                                                 virDomainIOThreadsInfoPtr **info,
>>                                                 unsigned int flags);
>> +int                  virDomainSetIOThreads(virDomainPtr domain,
>> +                                           unsigned int iothread_val,
>> +                                           unsigned char *cpumap,
>> +                                           int maplen,
>> +                                           unsigned int flags);
>>  
>>  /**
>>   * VIR_USE_CPU:
>> diff --git a/src/driver-hypervisor.h b/src/driver-hypervisor.h
>> index 2ce1a51..120d761 100644
>> --- a/src/driver-hypervisor.h
>> +++ b/src/driver-hypervisor.h
>> @@ -386,6 +386,13 @@ typedef int
>>                                  unsigned int flags);
>>  
>>  typedef int
>> +(*virDrvDomainSetIOThreads)(virDomainPtr domain,
>> +                            unsigned int iothread_val,
>> +                            unsigned char *cpumap,
>> +                            int maplen,
>> +                            unsigned int flags);
>> +
>> +typedef int
>>  (*virDrvDomainGetSecurityLabel)(virDomainPtr domain,
>>                                  virSecurityLabelPtr seclabel);
>>  
>> @@ -1260,6 +1267,7 @@ struct _virHypervisorDriver {
>>      virDrvDomainGetVcpus domainGetVcpus;
>>      virDrvDomainGetMaxVcpus domainGetMaxVcpus;
>>      virDrvDomainGetIOThreadsInfo domainGetIOThreadsInfo;
>> +    virDrvDomainSetIOThreads domainSetIOThreads;
>>      virDrvDomainGetSecurityLabel domainGetSecurityLabel;
>>      virDrvDomainGetSecurityLabelList domainGetSecurityLabelList;
>>      virDrvNodeGetSecurityModel nodeGetSecurityModel;
>> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
>> index f893b35..bf73773 100644
>> --- a/src/libvirt-domain.c
>> +++ b/src/libvirt-domain.c
>> @@ -7969,6 +7969,75 @@ virDomainIOThreadsInfoFree(virDomainIOThreadsInfoPtr info)
>>  
>>  
>>  /**
>> + * virDomainSetIOThreads:
>> + * @domain: a domain object
>> + * @iothread_val: either the thread_id to modify or a count of IOThreads
>> + *      to be added or removed from the domain depending on the @flags setting
> 
> IMO this would look nicer as two separate APIs:
> virDomainSetIOThreadPin
> virDomainSetIOThreadCount
> 

OK - fair enough. I was hoping to be able to "reuse" code, but changing
this to SetIOThreadPin is fine.

The other API will end up being the Add/Remove an IOThread, but will
require a bit of internal plumbing changes to allow for a removal of a
thread in the middle of the array.

Tks -

John
>> + * @cpumap: pointer to a bit map of real CPUs (in 8-bit bytes) (IN)
>> + *      Each bit set to 1 means that corresponding CPU is usable.
>> + *      Bytes are stored in little-endian order: CPU0-7, 8-15...
>> + *      In each byte, lowest CPU number is least significant bit.
>> + * @maplen: number of bytes in cpumap, from 1 up to size of CPU map in
>> + *      underlying virtualization system (Xen...).
>> + *      If maplen < size, missing bytes are set to zero.
>> + *      If maplen > size, failure code is returned.
>> + * @flags: bitwise-OR of supported virDomainIOThreadsFlags
>> + *
>> + * If the VIR_DOMAIN_IOTHREADS_PIN flag is set, the @iothread_val will be
>> + * an existing IOThread to be pinned
> 
> This doesn't feel like a flag. It changes what the API does, not how it
> does it.
> 
> Jan
> 

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