Ulrich Drepper wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Izik Eidus wrote:+ if (!kvm_x86_ops->dirty_bit_support()) { + spin_lock(&kvm->mmu_lock); + /* remove_write_access() flush the tlb */ + kvm_mmu_slot_remove_write_access(kvm, log->slot); + spin_unlock(&kvm->mmu_lock); + } else { + kvm_flush_remote_tlbs(kvm);
Hi.
It might not correspond to the common style, but I think a callback function ->dirty_bit_support is overkill. This is a function pointer the compiler cannot see through. Hence it's an indirect function call. But the implementation is always a simple yes/no (it seems). Indirect calls are rather expensive (most of the time they cannot be predicted right).
This function pointer will be called once every ioctl to get the dirty bit tracking, so i dont think it is a big issue (normal 30 times a sec)
Why not instead have a read-only data constants and have an inline function test that value? It means no function call and only one data access.
May be relevent, but i dont sure if it is needed optimization for this patch consider the amount of time ->dirty_bit_support() will be called
Also, you're inconsistent in the use of integers and true/false in the implementations of this function. Either use 0/1 or false/true.
I will fix it, thanks.
- -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkowv08ACgkQ2ijCOnn/RHR71ACdH3xr3XPnCLgsMMwdTawfehEN vs4An2DlErhU6SeanSYVIyP3eLB4sjsz =UZ32 -----END PGP SIGNATURE-----
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