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Kernel: Add fast-path for sys$gettid()

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The userspace locks are very aggressively calling sys$gettid() to find
out which thread ID they have.

Since syscalls are quite heavy, this can get very expensive for some
programs. This patch adds a fast-path for sys$gettid(), which makes it
skip all of the usual syscall validation and just return the thread ID
right away.

This cuts Kernel/Process.cpp compile time by ~18%, from ~29 to ~24 sec.
This commit is contained in:
Andreas Kling
2020-01-19 17:16:38 +01:00
parent 8d9dd1b04b
commit 5ce1cc89a0
1 changed files with 8 additions and 0 deletions
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8
Kernel/Syscall.cpp
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@@ -119,6 +119,14 @@ int handle(RegisterDump& regs, u32 function, u32 arg1, u32 arg2, u32 arg3)
void syscall_handler(RegisterDump regs)
{
// Special handling of the "gettid" syscall since it's extremely hot.
// FIXME: Remove this hack once userspace locks stop calling it so damn much.
if (regs.eax == SC_gettid) {
regs.eax = current->process().sys$gettid();
current->did_syscall();
return;
}
// Make sure SMAP protection is enabled on syscall entry.
clac();