c56004901f
This adds VM op batching to skas0. Rather than having a context switch to and from the userspace stub for each address space change, we write a number of operations to the stub data page and invoke a different stub which loops over them and executes them all in one go. The operations are stored as [ system call number, arg1, arg2, ... ] tuples. The set is terminated by a system call number of 0. Single operations, i.e. page faults, are handled in the old way, since that is slightly more efficient. For a kernel build, a minority (~1/4) of the operations are part of a set. These sets averaged ~100 in length, so for this quarter, the context switching overhead is greatly reduced. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
26 lines
387 B
ArmAsm
26 lines
387 B
ArmAsm
#include "uml-config.h"
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.globl syscall_stub
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.section .__syscall_stub, "x"
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syscall_stub:
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int $0x80
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mov %eax, UML_CONFIG_STUB_DATA
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int3
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.globl batch_syscall_stub
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batch_syscall_stub:
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mov $UML_CONFIG_STUB_DATA, %esp
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again: pop %eax
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cmpl $0, %eax
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jz done
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pop %ebx
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pop %ecx
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pop %edx
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pop %esi
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pop %edi
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pop %ebp
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int $0x80
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mov %eax, UML_CONFIG_STUB_DATA
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jmp again
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done: int3
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