[dpdk-dev] [RFC] net/virtio-user: avoid parsing process mappings
Burakov, Anatoly
anatoly.burakov at intel.com
Tue Aug 28 14:56:24 CEST 2018
On 28-Aug-18 9:42 AM, Tiwei Bie wrote:
> On Tue, Aug 28, 2018 at 09:12:38AM +0100, Burakov, Anatoly wrote:
>> On 28-Aug-18 8:53 AM, Tiwei Bie wrote:
> [...]
>>>
>>> - for (i = 0; i < num; ++i) {
>>> - mr = &msg->payload.memory.regions[i];
>>> - mr->guest_phys_addr = huges[i].addr; /* use vaddr! */
>>> - mr->userspace_addr = huges[i].addr;
>>> - mr->memory_size = huges[i].size;
>>> - mr->mmap_offset = 0;
>>> - fds[i] = open(huges[i].path, O_RDWR);
>>> + start_addr = (uint64_t)(uintptr_t)ms->addr;
>>> + end_addr = start_addr + ms->len;
>>> +
>>> + /*
>>> + * XXX workaround!
>>> + *
>>> + * For --single-file-segments case, offset should be:
>>> + * offset = rte_fbarray_find_idx(&msl->memseg_arr, ms) * msl->page_sz;
>>> + *
>>> + * But it's not true for non-single-file-segments case.
>>> + *
>>> + * This is a temporary workaround which assumes the file will
>>> + * also be mapped from the beginning in --single-file-segments
>>> + * case. It should be replaced when we have a memory API to
>>> + * get the offset.
>>
>> Yes, this is an unfortunate consequence of having split personalities in
>> memory subsystem. A good solution would be to just deprecate
>> non-single-file segments mode and always use it, but we cannot do that
>> because we support kernel versions that do not support fallocate() on
>> hugetlbfs (and it still leaves legacy mem mode, which effectively
>> behaves like non-single-file segments as far as virtio is concerned).
>>
>> How about we add this API in v2 for seg fd patchset?
>
> Sure, thanks!
>
> Besides, I saw another minor issue. When --legacy-mem
> and --single-file-segments are both specified, the EAL
> init doesn't fail, but fd can't be got successfully.
>
I'll have to look into this, because as far as i recall, i've submitted
a patch specifically prohibiting legacy mem combined with single file
segments. I'll double check though. Thanks for testing!
--
Thanks,
Anatoly
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