Remove slabs from the slab memory pool #30732

davidfowl · 2021-03-08T07:38:49Z

Slabs add an extra complication when trying to free blocks (blocks are attached to slabs and would need to be ref counted). Instead, since we can now directly allocate on the POH, we can see if slabs are still meaningful.
Use 4K arrays on the pinned heap
Remove the finalizer from MemoryPoolBlock
I didn't rename it

Investigating #27394

Looks slightly faster (allocation should be faster in general). I ran the plaintext benchmark.

Before:

| load                   |            |
| ---------------------- | ---------- |
| CPU Usage (%)          | 41         |
| Cores usage (%)        | 494        |
| Working Set (MB)       | 38         |
| Start Time (ms)        | 1          |
| First Request (ms)     | 96         |
| Requests/sec           | 2,293,809  |
| Requests               | 34,634,506 |
| Mean latency (ms)      | 1.25       |
| Max latency (ms)       | 53.75      |
| Bad responses          | 0          |
| Socket errors          | 0          |
| Read throughput (MB/s) | 288.76     |
| Latency 50th (ms)      | 0.98       |
| Latency 75th (ms)      | 1.43       |
| Latency 90th (ms)      | 1.84       |
| Latency 99th (ms)      | 14.78      |

After

| load                   |            |
| ---------------------- | ---------- |
| CPU Usage (%)          | 41         |
| Cores usage (%)        | 494        |
| Working Set (MB)       | 38         |
| Start Time (ms)        | 0          |
| First Request (ms)     | 105        |
| Requests/sec           | 2,343,985  |
| Requests               | 35,392,833 |
| Mean latency (ms)      | 1.19       |
| Max latency (ms)       | 49.37      |
| Bad responses          | 0          |
| Socket errors          | 0          |
| Read throughput (MB/s) | 295.07     |
| Latency 50th (ms)      | 0.96       |
| Latency 75th (ms)      | 1.41       |
| Latency 90th (ms)      | 1.79       |
| Latency 99th (ms)      | 16.58      |

The allocation rate is also lower (for more requests) in this run:

Before

| application                   |                           |
| ----------------------------- | ------------------------- |
| CPU Usage (%)                 | 100                       |
| Cores usage (%)               | 1,197                     |
| Working Set (MB)              | 70                        |
| Build Time (ms)               | 3,801                     |
| Start Time (ms)               | 175                       |
| Published Size (KB)           | 103,420                   |
| .NET Core SDK Version         | 6.0.100-preview.3.21158.6 |
| Max CPU Usage (%)             | 99                        |
| Max Working Set (MB)          | 73                        |
| Max GC Heap Size (MB)         | 10                        |
| Max Number of Gen 0 GCs / sec | 0.00                      |
| Max Number of Gen 1 GCs / sec | 0.00                      |
| Max Number of Gen 2 GCs / sec | 0.00                      |
| Max Time in GC (%)            | 0.00                      |
| Max Gen 0 Size (B)            | 0                         |
| Max Gen 1 Size (B)            | 0                         |
| Max Gen 2 Size (B)            | 0                         |
| Max LOH Size (B)              | 0                         |
| Max Allocation Rate (B/sec)   | 4,314,080                 |
| Max GC Heap Fragmentation     | 0                         |
| # of Assemblies Loaded        | 89                        |
| Max Exceptions (#/s)          | 852                       |
| Max Lock Contention (#/s)     | 337                       |
| Max ThreadPool Threads Count  | 28                        |
| Max ThreadPool Queue Length   | 220                       |
| Max ThreadPool Items (#/s)    | 158,591                   |
| Max Active Timers             | 0                         |
| IL Jitted (B)                 | 167,569                   |
| Methods Jitted                | 1,911                     |

After

| application                   |                           |
| ----------------------------- | ------------------------- |
| CPU Usage (%)                 | 100                       |
| Cores usage (%)               | 1,198                     |
| Working Set (MB)              | 70                        |
| Build Time (ms)               | 3,779                     |
| Start Time (ms)               | 221                       |
| Published Size (KB)           | 103,420                   |
| .NET Core SDK Version         | 6.0.100-preview.3.21158.6 |
| Max CPU Usage (%)             | 99                        |
| Max Working Set (MB)          | 72                        |
| Max GC Heap Size (MB)         | 10                        |
| Max Number of Gen 0 GCs / sec | 0.00                      |
| Max Number of Gen 1 GCs / sec | 0.00                      |
| Max Number of Gen 2 GCs / sec | 0.00                      |
| Max Time in GC (%)            | 0.00                      |
| Max Gen 0 Size (B)            | 0                         |
| Max Gen 1 Size (B)            | 0                         |
| Max Gen 2 Size (B)            | 0                         |
| Max LOH Size (B)              | 0                         |
| Max Allocation Rate (B/sec)   | 4,185,456                 |
| Max GC Heap Fragmentation     | 0                         |
| # of Assemblies Loaded        | 89                        |
| Max Exceptions (#/s)          | 896                       |
| Max Lock Contention (#/s)     | 359                       |
| Max ThreadPool Threads Count  | 32                        |
| Max ThreadPool Queue Length   | 178                       |
| Max ThreadPool Items (#/s)    | 161,368                   |
| Max Active Timers             | 0                         |
| IL Jitted (B)                 | 173,714                   |
| Methods Jitted                | 2,009                     |

- Use 4K arrays on the pinned heap - I didn't rename it

jkotalik · 2021-03-08T23:31:57Z

src/Shared/Buffers.MemoryPool/MemoryPoolBlock.cs


-            Memory = MemoryMarshal.CreateFromPinnedArray(slab.PinnedArray, _offset, _length);
+            var pinnedArray = GC.AllocateUninitializedArray<byte>(length, pinned: true);


https://docs.microsoft.com/en-us/dotnet/api/system.gc.allocateuninitializedarray?view=net-5.0 as an FYI to others reviewing.

We didn't zero-allocate the array before, correct?

https://github.com/dotnet/aspnetcore/pull/30732/files#diff-e7ec344376781603909872c55a122a48d16c5d9094284d51be214bd5d092fdfbL33

BrennanConroy · 2021-03-08T23:49:02Z

src/Shared/Buffers.MemoryPool/MemoryPoolBlock.cs

-            Memory = MemoryMarshal.CreateFromPinnedArray(slab.PinnedArray, _offset, _length);
+            var pinnedArray = GC.AllocateUninitializedArray<byte>(length, pinned: true);
+
+            Memory = MemoryMarshal.CreateFromPinnedArray(pinnedArray, 0, pinnedArray.Length);
        }

        /// <summary>
        /// Back-reference to the memory pool which this block was allocated from. It may only be returned to this pool.
        /// </summary>
        public SlabMemoryPool Pool { get; }


Remove? Only spot I see this used is when BLOCK_LEASE_TRACKING is defined.

Its used in dispose

Maoni0

looks like a good change to me!

Maoni0 · 2021-03-08T23:55:30Z

CC @cshung who's doing some perf work on POH

JamesNK · 2021-03-09T08:28:44Z

src/Shared/Buffers.MemoryPool/MemoryPoolBlock.cs

-        /// This object cannot be instantiated outside of the static Create method
-        /// </summary>
-        internal MemoryPoolBlock(SlabMemoryPool pool, MemoryPoolSlab slab, int offset, int length)
+        internal MemoryPoolBlock(SlabMemoryPool pool, int length)


SlabMemoryPool -> SlablessMemoryPool

😋

For real though, name change?

I think I'll rename it to PinnedBlockPool or something like that

Remove slabs from the slab memory pool

d769315

- Use 4K arrays on the pinned heap - I didn't rename it

davidfowl requested review from JamesNK, halter73 and sebastienros March 8, 2021 07:40

Pilchie added the area-servers label Mar 8, 2021

davidfowl requested review from BrennanConroy and jkotalik March 8, 2021 23:25

jkotalik reviewed Mar 8, 2021

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BrennanConroy reviewed Mar 8, 2021

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Maoni0 approved these changes Mar 8, 2021

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davidfowl marked this pull request as ready for review March 9, 2021 00:45

davidfowl merged commit 2e1063e into main Mar 9, 2021

davidfowl deleted the davidfowl/no-slabs branch March 9, 2021 08:22

JamesNK reviewed Mar 9, 2021

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davidfowl added this to the 6.0-preview3 milestone Mar 17, 2021

JamesNK mentioned this pull request Apr 8, 2021

Rename SlabMemoryPool #31609

Closed

amcasey added area-networking Includes servers, yarp, json patch, bedrock, websockets, http client factory, and http abstractions and removed area-runtime labels Aug 24, 2023

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Remove slabs from the slab memory pool #30732

Remove slabs from the slab memory pool #30732

davidfowl commented Mar 8, 2021 •

edited

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jkotalik Mar 8, 2021

davidfowl Mar 8, 2021

davidfowl Mar 8, 2021

BrennanConroy Mar 8, 2021

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BrennanConroy Mar 9, 2021

Maoni0 left a comment

Maoni0 commented Mar 8, 2021

JamesNK Mar 9, 2021

JamesNK Mar 9, 2021

davidfowl Mar 9, 2021


		Memory = MemoryMarshal.CreateFromPinnedArray(slab.PinnedArray, _offset, _length);
		var pinnedArray = GC.AllocateUninitializedArray<byte>(length, pinned: true);

Remove slabs from the slab memory pool #30732

Remove slabs from the slab memory pool #30732

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davidfowl commented Mar 8, 2021 • edited Loading

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davidfowl commented Mar 8, 2021 •

edited

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