Re: [Xen-devel] [PATCH 0/5] use mask operations instead of test_bit()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/10/15 05:40, Juergen Gross wrote:
> Instead of using test_bit() which is an atomic operation and limits
> the compiler's choices to do optimization, use logical ANDs with
> bitmasks where possible.
>
> The possible candidates have been detected by searching definitions
> of bitmasks in the form:
>
> #define MASK  1 << _MASK
>
> On x86 the resulting code is slightly smaller (about 2 bytes for each
> case, checked via disassembly in few examples).
>
> I'm quite sure I didn't replace a test_bit() call required to be
> atomic, but I'd be grateful for a thorough review especially in the
> scheduler.
>
>
> Juergen Gross (5):
>   xen: use masking operation instead of test_bit for RTDS bits
>   xen: use masking operation instead of test_bit for CSFLAG bits
>   xen: use masking operation instead of test_bit for VGCF bits
>   xen: use masking operation instead of test_bit for VPF bits
>   xen: use masking operation instead of test_bit for MCSF bits

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel