fc43aecbbd
I noticed that in Xenoblade 2, the game can end up spending a lot of time adding and removing tracking handles. One of the main causes of this is actually splitting existing handles, which does the following: - Remove existing handle from list - Update existing handle to end at split address, create new handle starting at split address - Add updated handle (left) to list - Add new handle (right) to list This costs 1 deletion and 2 insertions. When there are more handles, this gets a lot more expensive, as insertions are done by copying all values to the right, and deletions by copying values to the left. This PR simply allows it to look up the handle being split, and replace its entry with the new end address without insertion or deletion. This makes a split only cost one insertion and a binary search lookup (very cheap). This isn't all of the cost on Xenoblade 2, but it does significantly reduce it. There might be something else to this - we could find a way to reduce the handle count for the game (merging on deletion? buffer deletion?), we could use a different structure for virtual regions, as the current one is optimal for buffer lookups which nearly always read, memory tracking has more of a balance between read/write. That's for a later date though, this was an easy improvment.
106 lines
4.5 KiB
C#
106 lines
4.5 KiB
C#
using System;
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using System.Collections.Generic;
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namespace Ryujinx.Memory.Range
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{
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/// <summary>
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/// A range list that assumes ranges are non-overlapping, with list items that can be split in two to avoid overlaps.
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/// </summary>
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/// <typeparam name="T">Type of the range.</typeparam>
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class NonOverlappingRangeList<T> : RangeList<T> where T : INonOverlappingRange
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{
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/// <summary>
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/// Finds a list of regions that cover the desired (address, size) range.
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/// If this range starts or ends in the middle of an existing region, it is split and only the relevant part is added.
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/// If there is no matching region, or there is a gap, then new regions are created with the factory.
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/// Regions are added to the list in address ascending order.
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/// </summary>
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/// <param name="list">List to add found regions to</param>
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/// <param name="address">Start address of the search region</param>
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/// <param name="size">Size of the search region</param>
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/// <param name="factory">Factory for creating new ranges</param>
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public void GetOrAddRegions(List<T> list, ulong address, ulong size, Func<ulong, ulong, T> factory)
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{
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// (regarding the specific case this generalized function is used for)
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// A new region may be split into multiple parts if multiple virtual regions have mapped to it.
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// For instance, while a virtual mapping could cover 0-2 in physical space, the space 0-1 may have already been reserved...
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// So we need to return both the split 0-1 and 1-2 ranges.
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var results = new T[1];
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int count = FindOverlapsNonOverlapping(address, size, ref results);
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if (count == 0)
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{
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// The region is fully unmapped. Create and add it to the range list.
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T region = factory(address, size);
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list.Add(region);
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Add(region);
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}
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else
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{
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ulong lastAddress = address;
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ulong endAddress = address + size;
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for (int i = 0; i < count; i++)
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{
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T region = results[i];
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if (count == 1 && region.Address == address && region.Size == size)
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{
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// Exact match, no splitting required.
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list.Add(region);
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return;
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}
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if (lastAddress < region.Address)
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{
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// There is a gap between this region and the last. We need to fill it.
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T fillRegion = factory(lastAddress, region.Address - lastAddress);
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list.Add(fillRegion);
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Add(fillRegion);
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}
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if (region.Address < address)
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{
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// Split the region around our base address and take the high half.
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region = Split(region, address);
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}
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if (region.EndAddress > address + size)
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{
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// Split the region around our end address and take the low half.
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Split(region, address + size);
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}
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list.Add(region);
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lastAddress = region.EndAddress;
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}
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if (lastAddress < endAddress)
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{
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// There is a gap between this region and the end. We need to fill it.
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T fillRegion = factory(lastAddress, endAddress - lastAddress);
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list.Add(fillRegion);
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Add(fillRegion);
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}
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}
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}
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/// <summary>
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/// Splits a region around a target point and updates the region list.
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/// The original region's size is modified, but its address stays the same.
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/// A new region starting from the split address is added to the region list and returned.
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/// </summary>
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/// <param name="region">The region to split</param>
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/// <param name="splitAddress">The address to split with</param>
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/// <returns>The new region (high part)</returns>
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private T Split(T region, ulong splitAddress)
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{
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T newRegion = (T)region.Split(splitAddress);
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Update(region);
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Add(newRegion);
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return newRegion;
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}
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}
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}
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