1518101 - Add Nursery::allocateZeroedBuffer for inlined TypedArray construction

Status: RESOLVED FIXED

(Core :: JavaScript: GC, enhancement)

Description

[André Bargull [:anba]]

AllocateObjectBufferWithInit in the inlined TypedArray construction path is currently using malloc followed by memset to create zero-initialized memory for the TypedArray. This leads to sadness when doing µ-benchmarks for TypedArray construction performance, because memset touches every page of the allocated memory, which means the benchmark easily ends up allocating the complete system memory and we soon are measuring how fast the system can perform swap.

In numbers:
The following µ-benchmark reports about four seconds in the "total" count and effectively uses ~8GB memory on my system. When using calloc the "total" count is ~30ms and the memory usage is basically zero.

---
function f() {
    var r = 0;
    var t = dateNow();
    for (var i = 0; i < 2000; ++i) {
        var ta = new Int32Array(265000 + (i & 0x1));
        r += ta.length;
    }
    return [dateNow() - t, r];
}

var t = dateNow()
for (var i = 0; i < 5; ++i) print(f());
print("total:", (dateNow() - t));
---

Comment 1

[André Bargull [:anba]]

Attachment: bug1518101.patch

Adds Nursery::allocateZeroedBuffer, which almost the same as Nursery::allocateBuffer, except calloc instead of malloc is used.

Comment 2

[Jon Coppeard (:jonco)]

Comment on attachment 9034717 [details] [diff] [review]
bug1518101.patch

Review of attachment 9034717 [details] [diff] [review]:
-----------------------------------------------------------------

Great, thanks for fixing.

Comment 3

[André Bargull [:anba]]

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=22537cf2fd00e4af6132abd7a05827c37bd79eda

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/19051af76b77
Use calloc instead of malloc followed by memset for inlined TypedArray data allocation. r=jonco

Comment 5

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/19051af76b77