diff options
| author | Anton Ivanov <anton.ivanov@cambridgegreys.com> | 2018-11-22 14:45:13 +0000 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2018-12-27 22:48:20 +0100 |
| commit | 747b254ca2649d0c206385c7902fb8ac97a2b0b4 (patch) | |
| tree | ec37d6dde343cf0e24f9f063adf41e5798c517e1 /arch/um/kernel | |
| parent | 50109b5a03b4024eb6b8df3ab8f427625f54fe92 (diff) | |
um: Remove unnecessary faulted check in uaccess.c
It is not necessary to check if a fault has occured or not
after disabling pagefaults. kmap_atomic does that in all
cases and we can disable it for 64 bit where kmap is not needed
and a simple page_address would suffice.
dd if=/dev/zero of=/dev/null bs=1M count=1M
Before: 3.1GB/s. After: 3.5GB/s
There is a noticeable difference for file disk read and write
as well as less noticeable difference for network IO.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel')
| -rw-r--r-- | arch/um/kernel/skas/uaccess.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c index d450797a3a7c..7f06fdbc7ee1 100644 --- a/arch/um/kernel/skas/uaccess.c +++ b/arch/um/kernel/skas/uaccess.c @@ -62,27 +62,28 @@ static int do_op_one_page(unsigned long addr, int len, int is_write, jmp_buf buf; struct page *page; pte_t *pte; - int n, faulted; + int n; pte = maybe_map(addr, is_write); if (pte == NULL) return -1; page = pte_page(*pte); +#ifdef CONFIG_64BIT + pagefault_disable(); + addr = (unsigned long) page_address(page) + + (addr & ~PAGE_MASK); +#else addr = (unsigned long) kmap_atomic(page) + (addr & ~PAGE_MASK); +#endif + n = (*op)(addr, len, arg); - current->thread.fault_catcher = &buf; - - faulted = UML_SETJMP(&buf); - if (faulted == 0) - n = (*op)(addr, len, arg); - else - n = -1; - - current->thread.fault_catcher = NULL; - +#ifdef CONFIG_64BIT + pagefault_enable(); +#else kunmap_atomic((void *)addr); +#endif return n; } |