Commit Graph

136 Commits

Author SHA1 Message Date
Matteo Boschini
1873ff586b
metal : add gqa8 kernel to allow llama-2-70B on metal (#2459)
* Added gqa8 kernel to allow llama-2-70B on metal

* Update ggml-metal.m

Co-authored-by: Cebtenzzre <cebtenzzre@gmail.com>

* Extend kernel_mul_mat_f16_f32 to handle gqa broadcast

* Added ne03==ne13 assertion

---------

Co-authored-by: Cebtenzzre <cebtenzzre@gmail.com>
2023-08-01 10:43:12 +03:00
Shouzheng Liu
1aa18ef994
metal : concurrently dispatch commands (#2358)
* metal: concurrently dispatch commands

Function `ggml_metal_graph_find_concurrency` will run and write
commands that can be issued concurrently to metal context `concur_list`
array, when `ggml_metal_graph_compute` is called for the first time.

* metal: don't call find_concurrency automatically.

* metal : code style changes

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-07-25 15:00:19 +03:00
slaren
41c674161f
make rms_norm_eps a parameter (#2374)
* make rms_norm_eps a parameter

* add rms_norm_eps to command line

* fix baby llama, test-grad0

* use scientific notation for eps param in the help

ggml-ci
2023-07-24 17:57:12 +02:00
Georgi Gerganov
5b2b2dc6ae
ggml : sync (unary ops refactor, static-correctness) (#2370)
* ggml : sync (unary ops, tests)

ggml-ci

* tests : remove unnecessary funcs
2023-07-24 14:46:21 +03:00
slaren
95a6c595e7
ggml: move op parameters from tensors to ggml_tensor::op_params (#2333)
* ggml: move op parameters from tensors to ggml_tensor::op_params

* alibi: use memcpy for float params

* remove `src[1] = NULL` in ops
2023-07-23 14:36:02 +02:00
Jiahao Li
83a00ce69b
metal : support bcast add & dup & cont op (#2323) 2023-07-23 14:00:37 +03:00
Kawrakow
4d76a5f49b
Faster Q3_K implementation on Metal (#2307)
* Faster Q3_K on Metal

* Additional Q3_K speedup on Metal

* Q3_K for QK_K = 64

* Better Q3_K for QK_K = 64

21.6 ms/t -> 21.1 ms/t

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-07-21 17:05:30 +03:00
Kawrakow
e68c96f7fe
Faster Q2_K on Metal (#2297)
* Faster Q2_K on Metal

* Deleting unnoticed and dangereous trailing white space

* Fixed bug in new metal Q2_K implementation

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-07-21 10:44:40 +03:00
Kawrakow
e782c9e735
Faster Q5_K and Q6_K on Metal (#2294)
* Faster Q6_K on Metal

* Faster Q5_K on Metal

* Another Q5_K speedup

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-07-20 18:19:45 +03:00
Kawrakow
785829dfe8
Faster Q4_K on Metal (#2290)
Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-07-20 15:18:43 +03:00
Shouzheng Liu
417a85a001
metal: minor q4 optimization and reduce code size (#2248)
* metal: use uint16_t instead of uint8_t.

Apple GPU doesn't like uint8_t. For every operation on uint8_t
the gpu need to copy the uint8_t to an empty 16 bit register, then
it can issue other instructions.

For the matrix-vector multiplication kernel only, we observed a
340~350 GB/s memory read speed on M1 Max after this commit, which is
very close to the reported hardware limit.

* metal: update rms_norm kernel

This commit double the speed of rms_norm operations by using 512 threads
per threadgroup, combining with SIMD primitives to minimize the need for
thread group barriers.

* metal: use template to reduce size

Revert modifications on block_q4_0 and block_q4_1.
2023-07-20 13:32:22 +03:00
Xiao-Yong Jin
6e7cca4047
llama : add custom RoPE (#2054)
* Implement customizable RoPE

The original RoPE has pre-defined parameters

theta_i = 10000^(−2(i−1)/d), for i in [1, 2, ..., d/2]

Our customizable RoPE, ggml_rope_custom_inplace, uses

theta_i = scale * base^(−2(i−1)/d), for i in [1, 2, ..., d/2]

with the default matches the original

scale = 1.0
base = 10000

The new command line arguments
--rope-freq-base
--rope-freq-scale
set the two new RoPE parameter.

Recent researches show changing these two parameters extends the context limit with minimal loss.

1. Extending Context to 8K
   kaiokendev
   https://kaiokendev.github.io/til#extending-context-to-8k

2. Extending Context Window of Large Language Models via Positional Interpolation
   Shouyuan Chen, Sherman Wong, Liangjian Chen, Yuandong Tian
   https://arxiv.org/abs/2306.15595

3. NTK-Aware Scaled RoPE allows LLaMA models to have extended (8k+) context size without any fine-tuning and minimal perplexity degradation.
   https://www.reddit.com/user/bloc97
   https://www.reddit.com/r/LocalLLaMA/comments/14lz7j5/ntkaware_scaled_rope_allows_llama_models_to_have/

For the bold, try adding the following command line parameters to your favorite model:
-c 16384 --rope-freq-base 80000 --rope-freq-scale 0.5

* ggml-metal: fix custom rope

* common: fix argument names in help

* llama: increase MEM_REQ_EVAL for MODEL_3B

It avoids crashing for quantized weights on CPU.
Better ways to calculate the required buffer size would be better.

* llama: make MEM_REQ_EVAL depend on n_ctx

* server: use proper Content-Type in curl examples

Without the header Content-Type: application/json, curl will POST with
Content-Type: application/x-www-form-urlencoded

Though our simple server doesn't care, the httplib.h used has a limit
with CPPHTTPLIB_FORM_URL_ENCODED_PAYLOAD_MAX_LENGTH 8192

With Content-Type: application/json, we can send large json data.

* style : minor fixes, mostly indentations

* ggml : fix asserts

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-07-15 13:34:16 +03:00
Kawrakow
27ad57a69b
Metal: faster Q4_0 and Q4_1 matrix x vector kernels (#2212)
* 3-5% faster Q4_0 on Metal

* 7-25% faster Q4_1 on Metal

* Oops, forgot to delete the original Q4_1 kernel

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-07-14 11:46:21 +02:00
Shouzheng Liu
1cbf561466
metal : new q4_0 matrix-vector kernel (#2188)
Prefetch data to improve GPU utilization. ~48% faster for 33B model.
2023-07-12 23:10:55 +03:00
Spencer Sutton
5bf2a27718
ggml : remove src0 and src1 from ggml_tensor and rename opt to src (#2178)
* Add ggml changes

* Update train-text-from-scratch for change

* mpi : adapt to new ggml_tensor->src

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-07-11 19:31:10 +03:00
Evan Miller
5656d10599
mpi : add support for distributed inference via MPI (#2099)
* MPI support, first cut

* fix warnings, update README

* fixes

* wrap includes

* PR comments

* Update CMakeLists.txt

* Add GH workflow, fix test

* Add info to README

* mpi : trying to move more MPI stuff into ggml-mpi (WIP) (#2099)

* mpi : add names for layer inputs + prep ggml_mpi_graph_compute()

* mpi : move all MPI logic into ggml-mpi

Not tested yet

* mpi : various fixes - communication now works but results are wrong

* mpi : fix output tensor after MPI compute (still not working)

* mpi : fix inference

* mpi : minor

* Add OpenMPI to GH action

* [mpi] continue-on-error: true

* mpi : fix after master merge

* [mpi] Link MPI C++ libraries to fix OpenMPI

* tests : fix new llama_backend API

* [mpi] use MPI_INT32_T

* mpi : factor out recv / send in functions and reuse

* mpi : extend API to allow usage with outer backends (e.g. Metal)

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-07-10 18:49:56 +03:00
Qingyou Meng
1d656d6360
ggml : change ggml_graph_compute() API to not require context (#1999)
* ggml_graph_compute: deprecate using ggml_context, try resolve issue #287

* rewrite: no longer consider backward compitability; plan and make_plan

* minor: rename ctx as plan; const

* remove ggml_graph_compute from tests/test-grad0.c, but current change breaks backward

* add static ggml_graph_compute_sugar()

* minor: update comments

* reusable buffers

* ggml : more consistent naming + metal fixes

* ggml : fix docs

* tests : disable grad / opt + minor naming changes

* ggml : add ggml_graph_compute_with_ctx()

- backwards compatible API
- deduplicates a lot of copy-paste

* ci : enable test-grad0

* examples : factor out plan allocation into a helper function

* llama : factor out plan stuff into a helper function

* ci : fix env

* llama : fix duplicate symbols + refactor example benchmark

* ggml : remove obsolete assert + refactor n_tasks section

* ggml : fix indentation in switch

* llama : avoid unnecessary bool

* ggml : remove comments from source file and match order in header

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-07-07 19:24:01 +03:00
Aaron Miller
2f8cd979ec
metal : release buffers when freeing metal context (#2062) 2023-07-01 21:14:59 +03:00
Kawrakow
6769e944c7
k-quants : support for super-block size of 64 (#2001)
* k_quants: WIP super-blocks with 64 weights

* k_quants: WIP super-blocks with 64 weights

Q6_K scalar and AVX2 works

* k_quants: WIP super-blocks with 64 weights

Q4_K scalar and AVX2 works

* k_quants: WIP super-blocks with 64 weights

Q2_K scalar and AVX2 works. Q2_K is way too slow (it is actually slower
than the scalar implementation)

* k_quants: WIP super-blocks with 64 weights

Q3_K scalar and AVX2 works.

* k_quants: WIP super-blocks with 64 weights

Q5_K scalar and AVX2 works, and with that all
k_quants are done on AVX2 and scalar

* k_quants: WIP super-blocks with 64 weights

Q6_K working on CUDA. Cannot make it run quite as gast as
with super-blocks with 256 weigths: 8% slower on 4080,
20% slower on the 1660 (but there we fit 1 less layer on the
GPU because pf the larger model size), so some fraction of
these 20% is due to that,

* k_quants: WIP super-blocks with 64 weights

Q4_K working on CUDA. ~10% slower on GTX-1660,
16% slower on 4080.

* k_quants: WIP super-blocks with 64 weights

Q2_K working on CUDA. ~3% slower on GTX-1660,
10% slower on 4080.

* k_quants: WIP super-blocks with 64 weights

Q3_K working on CUDA.

* k_quants: WIP super-blocks with 64 weights

Q5_K working on CUDA, and with this CUDA is done.

* k_quants: WIP super-blocks with 64 weights

Q6_K working on ARM_NEON

* k_quants: WIP super-blocks with 64 weights

Q4_K working on ARM_NEON, but quite a bit slower than 256 weights

* k_quants: WIP super-blocks with 64 weights

Q2_K working on ARM_NEON, but quite a bit slower than 256 weights

* k_quants: WIP super-blocks with 64 weights

Q3_K working on ARM_NEON, but quite a bit slower than 256 weights.

* k_quants: WIP super-blocks with 64 weights

Q5_K working on ARM_NEON, but quite a bit slower than 256 weights.

With that, we have full support for ARM_NEON, although
performance is not quite there.

* k_quants: WIP super-blocks with 64 weights

Slightly more efficient Q3_K and Q5_K

* k_quants: WIP super-blocks with 64 weights

Another small improvement for Q3_K and Q5_K on ARM_NEON

* k_quants: WIP super-blocks with 64 weights

Yet another speedup for Q5_K on ARM_NEON.
We are now within 10% of the QK_K = 256 version.

* k_quants: WIP super-blocks with 64 weights

* We are able to pass preprocessor macros to the Metal
  compiler
* Q6_K works and is actually slightly more efficient than
  the QK_K = 256 version (25.2 ms vs 25.8 ms)

* k_quants: WIP super-blocks with 64 weights

Q4_K works on Metal and is actually slightly faster
than QK_K = 256 (21.95 ms vs 24.0 ms).

* k_quants: WIP super-blocks with 64 weights

Q2_K works on Metal and is very slightly faster
than QK_K = 256 (23.8 ms vs 24.2 ms).

* k_quants: WIP super-blocks with 64 weights

Q3_K works on Metal and is slightly faster
than QK_K = 256 (26.6 ms vs 28.3 ms).

* k_quants: WIP super-blocks with 64 weights

Q5_K works on Metal and is slightly faster
than QK_K = 256 (23.7 ms vs 26.3 ms).

* k_quants: call them _K, not _k, also on Metal

* k_quants: correctly define QK_K in llama.cpp

* Fixed bug in q4_K quantization added with the 64-block addition

* Simplify via lambda

* k_quants: swicth Q3_K to 4-bit scales when QK_K = 64

Otherwise there isn't much benefit from this
quantization type. There is some very slight loss
in accuracy, but we reduce size by ~7%.
E.g., for OpenLLaMA-3B, Q3_K_S perplexity is
8.6131 with 8-bit scales and 8.6352 with 4-bit,
while file size decreases from 1.53G to 1.44G.

* k_quants: switch Q4_K to 4-bit scales when QK_K = 64

 Here the loss in accuracy is greater than for Q3_K,
 but the Q4_K points still move further to the left on
 the perplexity vs size curve.

* k_quants: forgot to add the Metal changes in last commit

* k_quants: change Q5_K to be type 0 when QK_K = 64

Still needs AVX2 implementation

* k_quants: AVX2 implementation for new 64-weight Q5_K

* k_quants: 10% faster ARM_NEON Q5_K dot product

* k_quants: fixed issue caused by merging with master

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-26 19:43:07 +03:00
Georgi Gerganov
ce2c7d72e2
metal : handle buffers larger than device's maxBufferLength (#1826)
* metal : handle buffers larger than device's maxBufferLength

* metal : print more verbose device info + handle errors

* metal : fix prints for overlapping views

* metal : minimize view overlap to try to utilize device memory better
2023-06-18 09:09:47 +03:00
Georgi Gerganov
4f9c43e3bd
minor : warning fixes 2023-06-17 20:24:11 +03:00
Aaron Miller
0711a5f6dc
metal : add norm, cpy f16->f16, alibi kernels (#1823) 2023-06-17 17:37:49 +03:00
Georgi Gerganov
4bfcc855ab
metal : parallel command buffer encoding (#1860)
* metal : parallel command buffer encoding

* metal : determine number of command buffers based on gf->n_threads
2023-06-15 20:29:48 +03:00
Kawrakow
74a6d922f1
Metal implementation for all k_quants (#1807)
* metal : improve q4_K

28.3 -> 26.0 ms/token by avoiding a branch in the
calculation of the scales.

* metal : small improvement for Q4_K

* metal : still optimizing Q4_K

This commit pushes it down to 25.3 ms / token.

The crazy idea of using 6 bits for the scales is really costly on
Metal: if I remove the bit fiddling necessary to make the block
scales, time goes almost to the Q4_0 23 ms/token.

Before pushing the k-quants upstream I had a Q4_K variant that
had used 8-bit scales. It wasn't more accurate, used 0.125 bits more per weight,
was running slightly slower on the CPU (due to the larger model size
and being memory bound there), and the difference was entirely
negligible under CUDA. So, I decided to publish the version with 6-bit
scales. Perhaps I should re-consider and change to 8-bit scales?

* metal : some more optimizations

Q2_K: 25.4 ms/token
Q6_K: 27.3 ms/token
Q4_0: 22.8 ms/token
Q4_1: 23.1 ms/token

* metal : Q3_K support

Something is not quite right yet.

* metal : Q5_K support

Initial version achieves 31.2 ms/token, 210 GB/s

* metal : still not able to figure out why q3_K does not work

* Minor

* metal : yet another failed attempt to make q3_K work

* metal : optimize Q5_K

31.2 ms -> 27.8 ms.
250 GB/s.

* metal : q3_K still not working

Adding a heavily commented q3_K metal kernel to explain
my obviously faulty logic. Perhaps someone could spot the issue?

* metal : q3_K finally working

Not optimized at all.

What was the issue? The scales are not 4-bytes aligned,
and I was accessing them with a uint32_t pointer.
When I tried that on CUDA, I got an error (illegal memory access)
and added a memcpy to a local array of 3 uint32_t's.
But on Metal it told me there is no memcpy, so I tried
accessing directly. There is no error, just garbage results.
At some point I did try accessing the scales with an uint16_t
pointer (the scales are for sure 2-byte aligned), but was
still getting garbage. I guess, there must have been another bug.

No access to scales is via a uint16_t pointer and, after starting
from scratch from the C dequantize function, it finally works.

* metal : Q3_K 1st optimization pass

* metal : Q3_K second optimization pass - 29.6 ms/token

* metal : Q3_K cleanup

* metal : fixed accidentally broken Q2_K

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-12 22:39:21 +03:00
Kawrakow
8c0a10e64d
metal : fix failure to load model (#1817)
The number of buffers in the ggml context was left unitialized.
This leads to sporadic failures to load the model on
startup. It is actually strange that the failure occurred so
infrequantly.

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-12 14:31:36 +03:00
Andrei
303f5809f1
metal : fix issue with ggml-metal.metal path. Closes #1769 (#1782)
* Fix issue with ggml-metal.metal path

* Add ggml-metal.metal as a resource for llama target

* Update flake.nix metal kernel substitution
2023-06-10 17:47:34 +03:00
Kawrakow
e9b66ee982
metal : add Q4_1 implementation (#1785)
23.3 ms / token, so just ~1% slower than q4_0.
Achieves 290 GB/s memory throughput.

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-10 11:28:11 +03:00
AT
92f44ff7f7
metal : add GELU implementation (#1770)
Co-authored-by: Adam Treat <adam@nomic.ai>
2023-06-09 11:00:51 +03:00
Kawrakow
245fc3c37d
metal : faster q4_0 (#1775)
* metal : 8% faster q4_0

Avoid copying into local uchar4 anf float4.

* metal : 17% faster Q4_0

Use 64 threads in a thread group.

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-09 10:39:59 +03:00
Kawrakow
72ff5282bf
metal : add Q2_K implementation (#1762)
* metal : add Q2_K implementation

27.1 ms / token on M2 Max 30-core GPU, so about the
same speed as Q4_0. Memory throughput is ~156 GB/s.

The access pattern used in the Q2_K
CUDA implementation resulted in significantly lower
performance (~31 ms/token).

* Fixing merge conflicts

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-08 22:28:21 +03:00
Kawrakow
0f291e1f65
metal : Q6_K implementation (#1752)
* Metal implementation for Q4_K

Very slow for now:
42 ms / token, Q4_0 runs in 28 ms/token on my
30-core M2 Max GPU.

* Optimizing Q4_K on metal

The first token always takes longer, I guess because
the metal kernel is being jit-compiled.
So, using n = 128 to measure time.

At this point Q4_K takes 29.5 ms / token
compared to 27.2 ms / token for Q4_0.
Quite a bit better than the initial attempt,
but still not good enough.

* Optimizing q4_K metal dot some more

For n = 256 it is now 28.1 ms/token compared to
27 ms/token for q4_0.

* Fix after merge with master

* Metal implementation for Q6_K

Similar to the CUDA implementation.
No idea if this is the optimum for Metal, but the few
alternative variants I tried all had a lower performance.

We get 36.5 ms / token on M2 Max with 30 GPU cores.
This corresponds to ~200 GB/second throughput.

* clang-tidy : add config back

* Much better Q6_K implementation for metal

28.3 ms / token for 7B. Subtracting ~9 ms that is spent in
other compute graph operations, we are left with ~19 ms
for the matrix multiplications. The model is ~5.5 GB,
so we are getting 1000 / 19 * 5.5 = 290 GB/s!

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-08 19:46:22 +03:00
Kawrakow
4161bdc04d
metal : add Q4_K implementation (#1733)
* Metal implementation for Q4_K

Very slow for now:
42 ms / token, Q4_0 runs in 28 ms/token on my
30-core M2 Max GPU.

* Optimizing Q4_K on metal

The first token always takes longer, I guess because
the metal kernel is being jit-compiled.
So, using n = 128 to measure time.

At this point Q4_K takes 29.5 ms / token
compared to 27.2 ms / token for Q4_0.
Quite a bit better than the initial attempt,
but still not good enough.

* Optimizing q4_K metal dot some more

For n = 256 it is now 28.1 ms/token compared to
27 ms/token for q4_0.

* Fix after merge with master

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
2023-06-08 10:08:23 +03:00
Georgi Gerganov
44f906e853
metal : add f16 support 2023-06-06 20:21:56 +03:00
Spencer Sutton
590250f7a9
metal : add checks for buffer size (#1706)
Co-authored-by: Spencer Sutton <Spencer.Sutton@precisely.com>
2023-06-06 06:28:17 +03:00
kiltyj
9d0693bce3
metal : use shared buffers between CPU and GPU (#1696)
* Use MTLDevice.newBufferWithBytesNoCopy to share buffers between CPU and GPU

* Page-align buffers used by Metal

* Remove trailing whitespace

* Only import unistd.h for Metal builds

* metal : remove unnecessary copies

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
2023-06-05 23:24:04 +03:00
Georgi Gerganov
ecb217db4f
llama : Metal inference (#1642)
* mtl : export the LLaMA computation graph

* ci : disable temporary

* mtl : adapt the MNIST example as starter

* mtl : no need for mtl-export tool, add cli arg for main instead

* mtl : export just a small part of the graph for now to make it easier

* mtl : move MSL code into separate file for easy editing

* mtl : initial get_rows_q4_0 kernel

* mtl : confirmed get_rows_q4_0 is working correctly

* mtl : add rms_norm kernel + confirm working

* mtl : add mul kernel + confirm working

* mtl : initial mul_mat Q4 kernel (wrong results)

* mtl : mul_mat fixes (still wrong)

* mtl : another mul_mat Q4 (still does not work)

* mtl : working mul_mat q4

* ggml : fix handling of "view" ops in ggml_graph_import()

* mtl : add rope kernel

* mtl : add reshape and transpose handling

* ggml : store offset as opt arg for ggml_view_xd() operators

* mtl : add cpy kernel + handle view ops

* mtl : confirm f16 x f32 attention mul mat

* mtl : add scale kernel

* mtl : add diag_mask_inf kernel

* mtl : fix soft_max kernel

* ggml : update ggml_nbytes() to handle non-contiguous tensors

* mtl : verify V tensor contents

* mtl : add f32 -> f32 cpy kernel

* mtl : add silu kernel

* mtl : add non-broadcast mul kernel

* mtl : full GPU inference of the computation graph

* mtl : optimize rms_norm and soft_max kernels

* mtl : add f16 mat x f32 vec multiplication kernel

* mtl : fix bug in f16 x f32 mul mat + speed-up computation

* mtl : faster mul_mat_q4_0_f32 kernel

* mtl : fix kernel signature + roll inner loop

* mtl : more threads for rms_norm + better timing

* mtl : remove printfs from inner loop

* mtl : simplify implementation

* mtl : add save/load vocab to ggml file

* mtl : plug Metal inference into llama.cpp (very quick-n-dirty)

* mtl : make it work with main example

Lots of hacks but at least now it generates text

* mtl : preparing for merge

* mtl : clean-up ggml mtl interface + suport scratch / inplace

* mtl : remove temp / debug code

* metal : final refactoring and simplification

* Revert "ci : disable temporary"

This reverts commit 98c267fc77.

* metal : add comments

* metal : clean-up stuff, fix typos

* readme : add Metal instructions

* readme : add example for main
2023-06-04 23:34:30 +03:00