147 lines
6.3 KiB
C#
147 lines
6.3 KiB
C#
//-----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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// file="L4.Prefetch"
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// Project: StgSharp
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// AuthorGroup: Nitload
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// Copyright (c) Nitload. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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//
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// -----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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using System.ComponentModel;
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namespace StgSharp.HighPerformance.Memory
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{
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public unsafe partial class L4
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{
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public const int MaxActivateCacheLineCount = 1024;
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private partial void Prefetch()
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{
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if (CurrentPredict is null) {
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return;
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}
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if (_activeCount > MaxActivateCacheLineCount) {
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throw new OverflowException("Too many activated cache line in external reference.");
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}
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IL4Predict predict = CurrentPredict;
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int predictIndex = CurrentPredictIndex;
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Span<CacheLineDescription> span = new(_prediction, PredictionCount);
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PredictResult result = predict.Predict(span, out int actualCount);
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if ((result & PredictResult.Exhausted) != 0) {
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_exhausted = !TryGetNextPredict();
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}
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if (actualCount <= 0)
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{
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_exhausted = true;
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return;
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}
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int missIndex = 0;
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AgeAll();
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for (int i = 0; i < actualCount; i++)
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{
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ref CacheLineDescription handle = ref span[i];
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nuint address = handle.Address;
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if (!_map.TryGet(address, out _))
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{
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// miss and record
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span[missIndex] = handle;
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missIndex++;
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}
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}
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_predictors.RequestSpanOperation();
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Span<IL4Predict> predictorSpan = _predictors.AsSpan();
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try
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{
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// now prefetch the misses
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for (int i = 0; i < missIndex; i++)
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{
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CacheLineHead* head;
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ref CacheLineDescription pHandle = ref span[i];
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nuint address = pHandle.Address;
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int index;
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if (_map.TryGet(address, out nuint handle))
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{
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head = (CacheLineHead*)handle;
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index = head->Id;
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(*_eviction)[index] = 0; // reset eviction counter
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#region update predictor belonging
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int predictId = head->Predictor;
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IL4Predict belong = predictorSpan[predictId];
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// TODO 由于L4的缓存行改为“可变长度”缓存行，需要调整缓存行复用策略
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// This branch performs resident-line adoption rather than a simple policy
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// equality check. Returning true means the current predictor can keep using
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// the existing cache bytes without a write-back plus re-prefetch cycle.
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if (predict.IsSamePolicy(head->Profile, belong))
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{
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head->Predictor = (short)predictIndex;
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} else
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{
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// Compatibility failed, so the old owner must first flush its view of
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// the line before the new predictor rematerializes the cache bytes.
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belong.WriteBack(head->Origin, head->Profile, new ReadOnlySpan<byte>((byte*)head->Address, (int)head->Size));
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head->Profile = pHandle.MapPolicy;
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predict.Prefetch(head->Origin, head->Profile, new Span<byte>((byte*)head->Address, (int)head->Size));
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}
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#endregion
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continue;
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}
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int retryCount = 0, remain = missIndex - i;
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const int maxRetry = 1024;
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while (!TryGetEmptyLine(pHandle.Size, out index))
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{
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remain = Evict(remain);
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retryCount++;
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if (retryCount > maxRetry) {
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throw new OverflowException($"Failed to evict cache line after {maxRetry} retries.");
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}
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if (retryCount > maxRetry / 2) {
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Thread.Sleep(1);
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}
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}
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head = &_head[index];
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head->_id = index;
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head->Origin = address;
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head->Profile = pHandle.MapPolicy;
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head->RefCount = 0;
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head->Predictor = (short)predictIndex;
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// pre fetch them here
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predict.Prefetch(head->Origin, head->Profile, new Span<byte>((byte*)head->Address, (int)head->Size));
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_ = _map.TryAddOrSet(address, (nuint)head, out _);
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}
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_ = Interlocked.Add(ref _aheadCount, actualCount);
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}
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finally
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{
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_predictors.ReleaseSpanOperation();
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}
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}
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}
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}
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