On Thu, 2006-06-22 at 00:21 +0200, Andi Kleen wrote:
> > Can we use similar mechanism to access pda in vsyscall in x86_64 (by
> > storing the address of pda there).
>
>
> You mean in the kernel? %gs prefix is a lot faster than this.
>
Yes it is. And will work if we are okay to swap to kernel gs in
vsyscall code.
> Also the limit is only 20bit, not enough for a full address.
>
I was thinking of storing it is base address part of the descriptor and
then using the memory load to read it in vsyscall. (Keeping the p bit
to zero in the descriptor).
> For user space it's useful though, but I don't see any immediate uses
> other than cpu number and node number. For most purposes glibc TLS
> (which uses %fs) is probably sufficient.
cpu and node number are really important (for the reasons that you
mentioned in your initial mail on vgetcpu). In addition to that I was
thinking in terms of having some counters like nmi_count that is already
there and per cpu specific.
Besides, not having to use the tcache part in the proposed system call
seems to just make the interface cleaner.
-rohit
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
