vkGetQueryPoolResults fails when using VK_QUERY_RESULT_WITH_AVAILABILITY_BIT

[Grimelios]

When calling vkGetQueryPoolResults using the VK_QUERY_RESULT_WITH_AVAILABILITY_BIT bit, proper usage requires passing in twice the usual data size (and specifying twice the stride) in order to account for availability values. For example, this call (which doesn't use VK_QUERY_RESULT_WITH_AVAILABILITY_BIT) works like a charm:

let mut data = vec![0_u64; 2];

unsafe
{
    device.get_query_pool_results(
        query_pool, 
        0, 
        2, 
        &mut data, 
        QueryResultFlags::TYPE_64)?;
}

let elapsed = (data[1] - data[0]) as f32 * timestamp_period / 1000000.0;

An equivalent example using VK_QUERY_RESULT_WITH_AVAILABILITY_BIT is below. Note the doubled vector length, inclusion of QueryResultFlags::WITH_AVAILABILITY, and checking availability prior to utilizing query results.

let mut data = vec![0_u64; 4];

unsafe
{
    device.get_query_pool_results(
        query_pool, 
        0, 
        2, 
        &mut data, 
        QueryResultFlags::TYPE_64 | QueryResultFlags::WITH_AVAILABILITY)?;
}

if data[1] != 0
{
    let elapsed = (data[2] - data[0]) as f32 * timestamp_period / 1000000.0;
}

However, using ash, this call fails with a Vulkan validation message stating queryPool specified dataSize 16 which is incompatible with the specified query type and options.

The culprit is actually the stride parameter of vkGetQueryPoolResults. ash passes stride as mem::size_of::<T>() as _, which in this example is 8 (T is u64). With VK_QUERY_RESULT_WITH_AVAILABILITY_BIT, however, that stride should actually be 16, which accounts for interleaved query results and availabilities. This can be worked around by calling the relevant function directly:

let result = unsafe
{
    (device.fp_v1_0().get_query_pool_results)(
        device.handle(), 
        query_pool, 
        0, 
        2, 
        mem::size_of::<u64>() * data.len(), 
        data.as_mut_ptr() as *mut _,
        mem::size_of::<u64>() * 2,
        QueryResultFlags::TYPE_64 | QueryResultFlags::WITH_AVAILABILITY).result()
};

A non-breaking solution would be to double the stride if QueryResultFlags::WITH_AVAILABILITY is set. A breaking solution would be to modify the get_query_pool_results signature to include stride.

[MarijnS95]

Duplicate of #100 (comment), #639 (comment), #644 and #900.