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From: George Dunlap <george.dunlap@citrix.com>
To: Juergen Gross <jgross@suse.com>,
	Dario Faggioli <dario.faggioli@citrix.com>,
	xen-devel@lists.xenproject.org
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
	Meng Xu <mengxu@cis.upenn.edu>
Subject: Re: [PATCH 04/16] xen: sched: implement .init_pdata in all schedulers
Date: Wed, 23 Mar 2016 17:46:39 +0000	[thread overview]
Message-ID: <56F2D67F.9040401@citrix.com> (raw)
In-Reply-To: <56F0FC44.1070801@suse.com>

On 22/03/16 08:03, Juergen Gross wrote:
> On 18/03/16 20:04, Dario Faggioli wrote:
>> by borrowing some of the code of .alloc_pdata, i.e.,
>> the bits that perform initializations, leaving only
>> actual allocations in there, when any, which is the
>> case for Credit1 and RTDS.
>>
>> On the other hand, in Credit2, since we don't really
>> need any per-pCPU data allocation, everything that was
>> being done in .alloc_pdata, is now done in .init_pdata.
>> And the fact that now .alloc_pdata can be left undefined,
>> allows us to just get rid of it.
>>
>> Still for Credit2, the fact that .init_pdata is called
>> during CPU_STARTING (rather than CPU_UP_PREPARE) kills
>> the need for the scheduler to setup a similar callback
>> itself, simplifying the code.
>>
>> And thanks to such simplification, it is now also ok to
>> move some of the logic meant at double checking that a
>> cpu was (or was not) initialized, into ASSERTS (rather
>> than an if() and a BUG_ON).
>>
>> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
>> ---
>> Cc: George Dunlap <george.dunlap@eu.citrix.com>
>> Cc: Meng Xu <mengxu@cis.upenn.edu>
>> Cc: Juergen Gross <jgross@suse.com>
>> ---
>>  xen/common/sched_credit.c  |   20 +++++++++---
>>  xen/common/sched_credit2.c |   72 +++-----------------------------------------
>>  xen/common/sched_rt.c      |    9 ++++--
>>  3 files changed, 26 insertions(+), 75 deletions(-)
>>
>> diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
>> index 288749f..d4a0f5e 100644
>> --- a/xen/common/sched_credit.c
>> +++ b/xen/common/sched_credit.c
>> @@ -526,8 +526,6 @@ static void *
>>  csched_alloc_pdata(const struct scheduler *ops, int cpu)
>>  {
>>      struct csched_pcpu *spc;
>> -    struct csched_private *prv = CSCHED_PRIV(ops);
>> -    unsigned long flags;
>>  
>>      /* Allocate per-PCPU info */
>>      spc = xzalloc(struct csched_pcpu);
>> @@ -540,6 +538,19 @@ csched_alloc_pdata(const struct scheduler *ops, int cpu)
>>          return ERR_PTR(-ENOMEM);
>>      }
>>  
>> +    return spc;
>> +}
>> +
>> +static void
>> +csched_init_pdata(const struct scheduler *ops, void *pdata, int cpu)
>> +{
>> +    struct csched_private *prv = CSCHED_PRIV(ops);
>> +    struct csched_pcpu * const spc = pdata;
>> +    unsigned long flags;
>> +
>> +    /* cpu data needs to be allocated, but STILL uninitialized */
>> +    ASSERT(spc && spc->runq.next == spc->runq.prev && spc->runq.next == NULL);
> 
> This looks weird. I'd prefer:
> 
> ASSERT(spc && spc->runq.next == NULL && spc->runq.prev == NULL);

I prefer Juergen's suggestion too.  I wouldn't say it's worth respinning
over, but since you have to make adjustments to the previous patch
anyway, you might as well change this while you're at it.

With that change:

Reviewed-by: George Dunlap <george.dunlap@citrix.com>


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  reply	other threads:[~2016-03-23 17:46 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-18 19:03 [PATCH 00/16] Fixes and improvement (including hard affinity!) for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 01/16] xen: sched: fix locking when allocating an RTDS pCPU Dario Faggioli
2016-03-19  2:22   ` Meng Xu
2016-03-23 15:37   ` George Dunlap
2016-03-18 19:04 ` [PATCH 02/16] xen: sched: add .init_pdata hook to the scheduler interface Dario Faggioli
2016-03-22  8:08   ` Juergen Gross
2016-03-23 17:32   ` George Dunlap
2016-03-18 19:04 ` [PATCH 03/16] xen: sched: make implementing .alloc_pdata optional Dario Faggioli
2016-03-19  2:23   ` Meng Xu
2016-03-21 14:22   ` Jan Beulich
2016-03-23 17:36     ` George Dunlap
2016-03-24  9:43       ` Jan Beulich
2016-03-24 13:14         ` Dario Faggioli
2016-03-21 14:48   ` Juergen Gross
2016-03-21 15:07     ` Jan Beulich
2016-04-01 17:01       ` Dario Faggioli
2016-04-04  4:21         ` Juergen Gross
2016-04-04  6:13         ` Jan Beulich
2016-04-05 16:01           ` Dario Faggioli
2016-03-23 17:38   ` George Dunlap
2016-03-18 19:04 ` [PATCH 04/16] xen: sched: implement .init_pdata in all schedulers Dario Faggioli
2016-03-19  2:24   ` Meng Xu
2016-03-22  8:03   ` Juergen Gross
2016-03-23 17:46     ` George Dunlap [this message]
2016-03-18 19:04 ` [PATCH 05/16] xen: sched: move pCPU initialization in an helper Dario Faggioli
2016-03-23 17:51   ` George Dunlap
2016-03-23 18:09     ` George Dunlap
2016-03-24 13:21     ` Dario Faggioli
2016-03-18 19:04 ` [PATCH 06/16] xen: sched: prepare a .switch_sched hook for Credit1 Dario Faggioli
2016-03-18 19:04 ` [PATCH 07/16] xen: sched: prepare a .switch_sched hook for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 08/16] " Dario Faggioli
2016-03-19  2:24   ` Meng Xu
2016-03-21 14:25   ` Jan Beulich
2016-03-18 19:05 ` [PATCH 09/16] xen: sched: close potential races when switching scheduler to CPUs Dario Faggioli
2016-03-19  2:25   ` Meng Xu
2016-03-23 19:05   ` George Dunlap
2016-04-05 16:26     ` Dario Faggioli
2016-04-06 15:51       ` Dario Faggioli
2016-03-24 12:14   ` George Dunlap
2016-04-05 17:37     ` Dario Faggioli
2016-04-06 16:21       ` Dario Faggioli
2016-03-18 19:05 ` [PATCH 10/16] xen: sched: improve credit2 bootparams' scope, placement and signedness Dario Faggioli
2016-03-21 14:51   ` Juergen Gross
2016-03-24 12:20   ` George Dunlap
2016-03-18 19:05 ` [PATCH 11/16] xen: sched: on Credit2, don't reprogram the timer if idle Dario Faggioli
2016-03-24 15:03   ` George Dunlap
2016-03-18 19:05 ` [PATCH 12/16] xen: sched: fix per-socket runqueue creation in credit2 Dario Faggioli
2016-03-24 12:24   ` George Dunlap
2016-03-18 19:05 ` [PATCH 13/16] xen: sched: allow for choosing credit2 runqueues configuration at boot Dario Faggioli
2016-03-22  7:46   ` Juergen Gross
2016-03-24 12:36   ` George Dunlap
2016-03-18 19:05 ` [PATCH 14/16] xen: sched: per-core runqueues as default in credit2 Dario Faggioli
2016-03-24 12:37   ` George Dunlap
2016-03-18 19:06 ` [PATCH 15/16] xen: sched: scratch space for cpumasks on Credit2 Dario Faggioli
2016-03-18 19:27   ` Andrew Cooper
2016-03-24 12:44     ` George Dunlap
2016-03-24 12:56       ` Andrew Cooper
2016-03-24 13:10       ` Dario Faggioli
2016-03-18 19:06 ` [PATCH 16/16] xen: sched: implement vcpu hard affinity in Credit2 Dario Faggioli
2016-03-24 15:42   ` George Dunlap
2016-04-05 16:50     ` Dario Faggioli

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