Bug 178049

Summary:

[Linux] Use futex directly for WordLock

Product:

WebKit

Reporter:

Yusuke Suzuki <ysuzuki>

Component:

WebKit Misc.

Assignee:

Yusuke Suzuki <ysuzuki>

Status:

NEW

Severity:

Normal

CC:

fpizlo, mark.lam, saam

Priority:

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Patch	none

Yusuke Suzuki

Reported 2017-10-07 05:16:59 PDT

Let's use futex directly for WordLock.

Attachments
Patch (12.36 KB, patch) 2017-10-07 05:18 PDT, Yusuke Suzuki	no flags	Details Formatted Diff Diff
View All Add attachment proposed patch, testcase, etc.

Yusuke Suzuki

Comment 1 2017-10-07 05:18:16 PDT

Created attachment 323095 [details] Patch

Yusuke Suzuki

Comment 2 2017-10-07 05:22:31 PDT

WIP. Super simple implementation. It just uses upper most bit for isLockedBit. And using the other 31bit for futexing threads counting. The problem is that it only accepts 31bit threads... I'm not sure this is ok for bmalloc/WTF requirement. If it is not acceptable, we should make this unsigned meaning to, 0: unlocked, 1: locked, 2: locked, and having pending threads as it can be seen in https://www.akkadia.org/drepper/futex.pdf.

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