ollama/kvcache/wrapper.go
Jesse Gross 854a9195f3 attention: Remove unnecessary contiguous operations
Prior to performing attention, we need to permute query, key
and value. Currently we call Contiguous after each of these
permutations, which is correct but expensive. Avoiding the
3 calls to Contiguous increases performance by over 20%.

The permutations of query and key do not violate the continuity
rules for mulmat and the Contiguous call can be simply removed.

Value requires a different permutation and does require Contiguous.
However, we can use the copy into the cache as a way to perform this
without further overhead.

To support this and avoid unexpected tensor shapes that are seen by
models, we need tighter integration between attention, cache
and backend. Future optimization will also likely need this structure
 - for example, flash attention has special padding requirements in
the cache and other backends may have their own needs.

This further contains the operations that go into attention so that
these and other optimizations can be handled transparently. Models
that have special requirements for attention can still implement
their own version of it.
2025-03-01 20:53:23 -08:00

100 lines
2.2 KiB
Go

package kvcache
import (
"math"
"github.com/ollama/ollama/ml"
)
// Wrapper cache is a container for multiple types of caches,
// such as for the encoding and decoding portions of a model.
type WrapperCache struct {
// caches we are wrapping
caches []Cache
// cache to be used for this layer
curType int
}
func NewWrapperCache(caches ...Cache) *WrapperCache {
return &WrapperCache{
caches: caches,
}
}
func (c *WrapperCache) Init(backend ml.Backend, dtype ml.DType, capacity int32) {
for _, cache := range c.caches {
cache.Init(backend, dtype, capacity)
}
}
func (c *WrapperCache) SetConfig(config ml.CacheConfig) {
for _, cache := range c.caches {
cache.SetConfig(config)
}
}
func (c *WrapperCache) Close() {
for _, cache := range c.caches {
cache.Close()
}
}
func (c *WrapperCache) StartForward(ctx ml.Context, positions []int32, seqs []int) error {
for i, cache := range c.caches {
err := cache.StartForward(ctx, positions, seqs)
if err != nil {
// unwind on error - Remove with endIndex set to math.MaxInt32 does not fail
for j := i - 1; j >= 0; j-- {
for k := range positions {
_ = c.caches[j].Remove(seqs[k], positions[k], math.MaxInt32)
}
}
return err
}
}
c.curType = 0
return nil
}
func (c *WrapperCache) SetLayer(layer int) {
for _, cache := range c.caches {
cache.SetLayer(layer)
}
}
func (c *WrapperCache) SetLayerType(layerType int) {
c.curType = layerType
}
func (c *WrapperCache) UnderlyingCache() Cache {
return c.caches[c.curType]
}
func (c *WrapperCache) Get(ctx ml.Context) (ml.Tensor, ml.Tensor, ml.Tensor) {
return c.caches[c.curType].Get(ctx)
}
func (c *WrapperCache) Put(ctx ml.Context, key, value ml.Tensor) {
c.caches[c.curType].Put(ctx, key, value)
}
func (c *WrapperCache) CopyPrefix(srcSeq, dstSeq int, len int32) {
for _, cache := range c.caches {
cache.CopyPrefix(srcSeq, dstSeq, len)
}
}
func (c *WrapperCache) Remove(seq int, beginIndex, endIndex int32) error {
// If the one of these fails, the caller is supposed to retry with endIndex set to math.MaxInt32, which should not fail
for _, cache := range c.caches {
err := cache.Remove(seq, beginIndex, endIndex)
if err != nil {
return err
}
}
return nil
}