From: Yi Liu <yi.l.liu@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
Alex Williamson <alex.williamson@redhat.com>
Cc: <kevin.tian@intel.com>, <joro@8bytes.org>, <robin.murphy@arm.com>,
<eric.auger@redhat.com>, <nicolinc@nvidia.com>,
<kvm@vger.kernel.org>, <chao.p.peng@linux.intel.com>,
<iommu@lists.linux.dev>, <baolu.lu@linux.intel.com>,
<zhenzhong.duan@intel.com>, <jacob.jun.pan@intel.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2 1/4] ida: Add ida_get_lowest()
Date: Tue, 23 Apr 2024 15:19:56 +0800 [thread overview]
Message-ID: <4bac4087-77d8-45c1-852a-1c6a37044431@intel.com> (raw)
In-Reply-To: <20240419140047.GF3050601@nvidia.com>
On 2024/4/19 22:00, Jason Gunthorpe wrote:
> On Fri, Apr 19, 2024 at 07:55:04AM -0600, Alex Williamson wrote:
>> On Fri, 19 Apr 2024 21:43:17 +0800
>> Yi Liu <yi.l.liu@intel.com> wrote:
>>
>>> On 2024/4/19 01:12, Jason Gunthorpe wrote:
>>>> On Thu, Apr 18, 2024 at 10:23:14AM -0600, Alex Williamson wrote:
>>>>>> yep. maybe we can start with the below code, no need for ida_for_each()
>>>>>> today.
>>>>>>
>>>>>>
>>>>>> int id = 0;
>>>>>>
>>>>>> while (!ida_is_empty(&pasid_ida)) {
>>>>>> id = ida_find_first_range(pasid_ida, id, INT_MAX);
>>>>>
>>>>> You've actually already justified the _min function here:
>>>>>
>>>>> static inline int ida_find_first_min(struct ida *ida, unsigned int min)
>>>>> {
>>>>> return ida_find_first_range(ida, min, ~0);
>>>>> }
>>>>
>>>> It should also always start from 0..
>>>
>>> any special reason to always start from 0? Here we want to loop all the
>>> IDs, and remove them. In this usage, it should be more efficient if we
>>> start from the last found ID.
>>
>> In the above version, there's a possibility of an infinite loop, in the
>> below there's not. I don't think the infinite loop is actually
>> reachable, but given the xarray backend to ida I'm not sure you're
>> gaining much to restart after the previously found id either. Thanks,
>
> Right, there is no performance win on xarray and it only risks an
> infinite loop compared to:
>
>>>> while ((id = ida_find_first(pasid_ida)) != EMPTY_IDA) {
>>>> ida_remove(id);
>>>> }
>
> Which does not by construction
thanks, got you two. :) Let's go with below. < 0 should mean
no ID found.
while ((id = ida_find_first(pasid_ida)) < 0) {
ida_free(id);
}
--
Regards,
Yi Liu
next prev parent reply other threads:[~2024-04-23 7:16 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-12 8:21 [PATCH v2 0/4] vfio-pci support pasid attach/detach Yi Liu
2024-04-12 8:21 ` [PATCH v2 1/4] ida: Add ida_get_lowest() Yi Liu
2024-04-16 16:03 ` Alex Williamson
2024-04-18 7:02 ` Yi Liu
2024-04-18 16:23 ` Alex Williamson
2024-04-18 17:12 ` Jason Gunthorpe
2024-04-19 13:43 ` Yi Liu
2024-04-19 13:55 ` Alex Williamson
2024-04-19 14:00 ` Jason Gunthorpe
2024-04-23 7:19 ` Yi Liu [this message]
2024-04-19 13:40 ` Yi Liu
2024-04-12 8:21 ` [PATCH v2 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices Yi Liu
2024-04-16 9:01 ` Tian, Kevin
2024-04-16 9:24 ` Yi Liu
2024-04-16 9:47 ` Tian, Kevin
2024-04-18 7:04 ` Yi Liu
2024-04-23 12:43 ` Jason Gunthorpe
2024-04-24 0:33 ` Tian, Kevin
2024-04-24 4:48 ` Yi Liu
2024-04-12 8:21 ` [PATCH v2 3/4] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT Yi Liu
2024-04-16 9:13 ` Tian, Kevin
2024-04-16 9:36 ` Yi Liu
2024-04-23 12:45 ` Jason Gunthorpe
2024-04-12 8:21 ` [PATCH v2 4/4] vfio: Report PASID capability via VFIO_DEVICE_FEATURE ioctl Yi Liu
2024-04-16 9:40 ` Tian, Kevin
2024-04-16 17:57 ` Alex Williamson
2024-04-17 7:09 ` Tian, Kevin
2024-04-17 20:25 ` Alex Williamson
2024-04-18 0:21 ` Tian, Kevin
2024-04-18 8:23 ` Yi Liu
2024-04-18 16:34 ` Alex Williamson
2024-04-23 12:39 ` Jason Gunthorpe
2024-04-24 0:24 ` Tian, Kevin
2024-04-24 13:59 ` Jason Gunthorpe
2024-04-16 8:38 ` [PATCH v2 0/4] vfio-pci support pasid attach/detach Tian, Kevin
2024-04-16 17:50 ` Jason Gunthorpe
2024-04-17 7:16 ` Tian, Kevin
2024-04-17 12:20 ` Jason Gunthorpe
2024-04-17 23:02 ` Alex Williamson
2024-04-18 0:06 ` Tian, Kevin
2024-04-18 9:03 ` Yi Liu
2024-04-18 20:37 ` Alex Williamson
2024-04-19 5:52 ` Tian, Kevin
2024-04-19 16:35 ` Alex Williamson
2024-04-23 7:43 ` Tian, Kevin
2024-04-23 12:01 ` Jason Gunthorpe
2024-04-23 23:47 ` Tian, Kevin
2024-04-24 0:12 ` Jason Gunthorpe
2024-04-24 2:57 ` Tian, Kevin
2024-04-24 12:29 ` Baolu Lu
2024-04-24 14:04 ` Jason Gunthorpe
2024-04-24 5:19 ` Tian, Kevin
2024-04-24 14:15 ` Jason Gunthorpe
2024-04-24 18:38 ` Alex Williamson
2024-04-24 18:45 ` Jason Gunthorpe
2024-04-24 18:24 ` Alex Williamson
2024-04-24 18:36 ` Jason Gunthorpe
2024-04-24 20:13 ` Alex Williamson
2024-04-26 14:11 ` Jason Gunthorpe
2024-04-26 20:13 ` Alex Williamson
2024-04-28 6:19 ` Tian, Kevin
2024-04-29 7:43 ` Yi Liu
2024-04-29 17:15 ` Jason Gunthorpe
2024-04-29 17:44 ` Jason Gunthorpe
2024-04-27 5:05 ` Christoph Hellwig
2024-04-25 9:26 ` Yi Liu
2024-04-25 12:58 ` Alex Williamson
2024-04-26 9:01 ` Yi Liu
2024-04-19 13:59 ` Jason Gunthorpe
2024-04-23 7:58 ` Yi Liu
2024-04-23 12:05 ` Jason Gunthorpe
2024-04-19 13:34 ` Jason Gunthorpe
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