Bug 1469757 - kernel: Implement vDSO support for getpid
Summary: kernel: Implement vDSO support for getpid
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: rawhide
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks: 1469670
TreeView+ depends on / blocked
 
Reported: 2017-07-11 19:14 UTC by Florian Weimer
Modified: 2026-07-24 14:54 UTC (History)
8 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: Bug
Embargoed:


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Description Florian Weimer 2017-07-11 19:14:07 UTC
glibc used to have a getpid wrapper which cached the current PID in userspace.  It turned out that this cache was difficult to maintain because certain system calls (with specific flags) invalidate it, while at the same time, the semantics of those system calls do not permit unconditional invalidation of the cache.

However, as pointed out in bug 1443976 comment 5 and bug 1469670, the system call overhead introduces a substantial performance regression in some cases.  Therefore, it would be nice to have a getpid implementation in the vDSO which does not perform a context switch.

Comment 1 Charles Haithcock 2026-07-24 14:54:17 UTC
This report has not received an update in over 90 days. If this issue is still relevant to you, please do not hesitate to update this report with any relevant details on recent investigative steps or changes and we will absolutely work to understand how to best move forward. Otherwise, this bug report will need to be closed in 30 days. No worries, however; should you need still assistance after the report is closed, please do not hesitate to create a new bug report referencing this report and with any new details on the matter. 

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