- On Oct 13, 2017, at 10:50 AM, Mathieu Desnoyers
mathieu.desnoy...@efficios.com wrote:
> - On Oct 13, 2017, at 9:57 AM, One Thousand Gnomes
> gno...@lxorguk.ukuu.org.uk wrote:
>
>>> A maximum limit of 16 operations per cpu_opv syscall invocation is
>>> enforced, so user-space cannot gen
- On Oct 13, 2017, at 10:50 PM, Andi Kleen a...@firstfloor.org wrote:
>> +pagefault_disable();
>> +switch (len) {
>> +case 1:
>> +if (__get_user(tmp._u8, (uint8_t __user *)p))
>> +goto end;
>> +tmp._u8 += (uint8_t)count;
>> +i
> + pagefault_disable();
> + switch (len) {
> + case 1:
> + if (__get_user(tmp._u8, (uint8_t __user *)p))
> + goto end;
> + tmp._u8 += (uint8_t)count;
> + if (__put_user(tmp._u8, (uint8_t __user *)p))
> + goto e
On Thu, Oct 12, 2017 at 4:03 PM, Mathieu Desnoyers
wrote:
> This new cpu_opv system call executes a vector of operations on behalf
> of user-space on a specific CPU with preemption disabled. It is inspired
> from readv() and writev() system calls which take a "struct iovec" array
> as argument.
>
- On Oct 13, 2017, at 9:57 AM, One Thousand Gnomes
gno...@lxorguk.ukuu.org.uk wrote:
>> A maximum limit of 16 operations per cpu_opv syscall invocation is
>> enforced, so user-space cannot generate a too long preempt-off critical
>> section.
>
> Except that all the operations could be going
> A maximum limit of 16 operations per cpu_opv syscall invocation is
> enforced, so user-space cannot generate a too long preempt-off critical
> section.
Except that all the operations could be going to mmapped I/O space and if
I pick the right targets could take quite a long time to complete. It
This new cpu_opv system call executes a vector of operations on behalf
of user-space on a specific CPU with preemption disabled. It is inspired
from readv() and writev() system calls which take a "struct iovec" array
as argument.
The operations available are: comparison, memcpy, add, or, and, xor,
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