On 2010-10-01 16:50, J. Bruce Fields wrote:
> On Thu, Sep 30, 2010 at 08:47:46PM +0200, Benny Halevy wrote:
>> The existing code adjusted it based on the worst case scenario for the returned
>> bitmap and the best case scenario for the supported attrs attribute.
>
> Looks fine, thanks. Mind if I just ditch the unlikely()s? I know,
> they've been there for a while, but I'm just skeptical of their value on
> anything but the most unbelievably hot optimized-to-death code paths.
Well, they don't bother me so I don't the value of ditching them either :)
They're supposed to help branch prediction thus optimizing the common
code paths on the expense of the unlikely path but I too didn't measure
their affect.
Bottom line is that I don't have and strong reservations either for or
against them in this case :)
Benny
>
> --b.
>
>>
>> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
>> ---
>> fs/nfsd/nfs4xdr.c | 14 ++++++++++----
>> 1 files changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
>> index 1a468bb..f48d891 100644
>> --- a/fs/nfsd/nfs4xdr.c
>> +++ b/fs/nfsd/nfs4xdr.c
>> @@ -1805,19 +1805,23 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
>> goto out_nfserr;
>> }
>> }
>> - if ((buflen -= 16) < 0)
>> - goto out_resource;
>>
>> if (unlikely(bmval2)) {
>> + if ((buflen -= 16) < 0)
>> + goto out_resource;
>> WRITE32(3);
>> WRITE32(bmval0);
>> WRITE32(bmval1);
>> WRITE32(bmval2);
>> } else if (likely(bmval1)) {
>> + if ((buflen -= 12) < 0)
>> + goto out_resource;
>> WRITE32(2);
>> WRITE32(bmval0);
>> WRITE32(bmval1);
>> } else {
>> + if ((buflen -= 8) < 0)
>> + goto out_resource;
>> WRITE32(1);
>> WRITE32(bmval0);
>> }
>> @@ -1828,15 +1832,17 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
>> u32 word1 = nfsd_suppattrs1(minorversion);
>> u32 word2 = nfsd_suppattrs2(minorversion);
>>
>> - if ((buflen -= 12) < 0)
>> - goto out_resource;
>> if (!aclsupport)
>> word0 &= ~FATTR4_WORD0_ACL;
>> if (!word2) {
>> + if ((buflen -= 12) < 0)
>> + goto out_resource;
>> WRITE32(2);
>> WRITE32(word0);
>> WRITE32(word1);
>> } else {
>> + if ((buflen -= 16) < 0)
>> + goto out_resource;
>> WRITE32(3);
>> WRITE32(word0);
>> WRITE32(word1);
>> --
>> 1.7.2.3
>>
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