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mem: Allocate at 4KiB boundaries in the fallback buffer pool. #8705

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Merged
easwars merged 2 commits into from
Nov 17, 2025
Merged

mem: Allocate at 4KiB boundaries in the fallback buffer pool. #8705

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mem: Allocate at 4KiB boundaries in the fallback buffer pool.
cjc25 Nov 13, 2025
4095e70
Address PR comments
cjc25 Nov 13, 2025
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13 changes: 11 additions & 2 deletions mem/buffer_pool.go
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Original file line number Diff line number Diff line change
Expand Up @@ -38,9 +38,11 @@ type BufferPool interface {
Put(*[]byte)
}

const goPageSize = 4 << 10 // 4KiB. N.B. this must be a power of 2.

var defaultBufferPoolSizes = []int{
256,
4 << 10, // 4KB (go page size)
goPageSize,
16 << 10, // 16KB (max HTTP/2 frame size used by gRPC)
32 << 10, // 32KB (default buffer size for io.Copy)
1 << 20, // 1MB
Expand Down Expand Up @@ -172,7 +174,14 @@ func (p *simpleBufferPool) Get(size int) *[]byte {
p.pool.Put(bs)
}

b := make([]byte, size)
// If we're going to allocate, round up to the nearest page. This way if
// requests frequently arrive with small variation we don't allocate
// repeatedly if we get unlucky and they increase over time. By default we
// only allocate here if size > 1MiB. Because goPageSize is a power of 2, we
// can round up efficiently.
allocSize := (size + goPageSize - 1) & ^(goPageSize - 1)

b := make([]byte, size, allocSize)
return &b
}

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