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When ggml_backend_buffer_free() is called, the device memory
is released but not all backends consistently release the actual
ggml_backend_buffer_t in system RAM, causing a memory leak.

Bug #10040

For every forward pass through the model, we need to allocate input
tensors: tokens, images, positions, outputs and masks. These get
allocated in system memory.

However, when we close the context that the tensors were allocated
through, the metadata gets freed but the actual backend memory does
not. This results in a significant memory leak.

This makes it so that all the memory allocated through a context
gets freed when it is closed.

Fixes #10040

Allocating (and in particular, freeing) memory from CUDA host buffers
is expensive and can cause a significant performance hit if we do
it for every token. Using normal system memory avoids this issue
and also gives the OS more flexibility to manage it.

There is no performance impact from this patch directly (either
positive or negative) but it makes a difference once we start
freeing memory correctly.

Context is currently mixed between pointer and value receivers. Change
this to be all pointer receivers so don't have to reason about whether
the things we are updating in the struct will be retained.

Sometimes loading the GGUF file fails with:
panic: context canceled

This is probably a filesystem error but it doesn't provide any
information about what happened.

Currently, the KV cache and graph are lazily allocated as needed.
The cache is fully allocated on first use of the corresponding
layer whereas the graph grows with the size of the context.

This can be an issue if another application allocates more VRAM
after we do our calculations - Ollama will crash in the middle of
inference. If we instead allocate the maximum needed memory at
startup of the runner, we will either succeed or fail at that point
rather than at some surprising time in the future.

Currently, this only generates a worst case batch for text, which
means that vision models may get a partial allocation and continue
to lazily allocate the rest.

If there is a CUDA OOM, we currently don't check the return value
and will evetually segfault. This checks for the problem and generates
a Go error. At the moment, this will still result in a panic but having
the error is the first step to being able to handle it more gracefully.

improves model loading times on network-based filesystems
such as GCS fuse by creating a dedicated file descriptor for each
section of the file being read, reducing seeking

Mistral is a popular research lab making open source models. This updates
the forward pass of llama architecture models to support both llama models
and mistral models by accounting for additional metadata present in mistral
models, and finding the correct dimensions for the output projection.

Model implementations should use Input for all of their tensors
supplied to the model. This includes tensors that relate to the
outputs, which is confusing since there is also an Output funciton.

Since Output is only used internally in GGML and not used by any
model implementations, we can remove it from the interface to
reduce confusion.

This enables the runner to report progress back to the Ollama server,
both for showing status to the user and also to prevent the server
from killing the runner if it thinks things have stalled.

Most of the infrastructure was already there, this extends it to
be available to the backends.

When converting a ggml model if there is a failure to read tensor data a nil error value was being returned. It should be assigned to the actual error from reading.

* macOS has different definition per info from @mxyng

Signed-off-by: shane.xb.qian <shane.qian@foxmail.com>

this produces a nicer output since both positive and negative values
produces the same width

Similar to the llama engine, quantizing the KV cache requires
flash attention to be enabled through the Ollama server.

Backends can impose additional alignment requirements on buffer sizes.
We should ensure that we meet these or allocations can fail.

this ensures the tensor is created on the right buffer type for backends
such as cpu

temporary until tensor loading can accurately account for vision models