On Thu, Sep 26, 2013 at 2:34 PM, David Disseldorp <ddiss@xxxxxxx> wrote:
> Hi Steve,
>
> On Thu, 26 Sep 2013 12:22:49 -0500
> Steve French <smfrench@xxxxxxxxx> wrote:
>
>> Windows clients seem to max out at 16MB chunk size when doing copy
>> offload. I would like to increase chunk size larger than that if
>> network bandwidth (returned at mount time in SMB3 on the query network
>> interfaces FSCTL) is large enough, and response time is not more than
>> 100 (?) milliseconds.
>
> Sounds good, though with Samba and Btrfs the request latency will be
> heavily effected by whether the FSCTL_SRV_COPYCHUNK wire request byte
> offsets and lengths align to the Btrfs sector-size (4K by default
> IIRC).
> If they do align, then each chunk in the request can be mapped to a
> BTRFS_IOC_CLONE_RANGE ioctl. Otherwise, we need to fall back to a
> server-side local read/write.
>
> We should be able to provide underlying filesystem alignment
> requirements to SMB clients via the new FileFSSectorSizeInformation
> ioctl, but it's not currently supported by Samba.
I just posted a patch for the kernel client to request this information (when
SMB3 is requested) but Windows 8 for both SSD and spinning disk
was returning 512 byte for logical and physical and best
performance sector sizes. So alignment for the CopyChunk chunks
that I will request on refcopy request will be straightforward.
It was great that the system reports the SSD vs. non-SSD correctly
with this new FSCTL. Hopefully we can add a Samba VFS routine
to report this info - although not sure how we can request info
from the kernel to fill in these flags and fields.
#define SSINFO_FLAGS_ALIGNED_DEVICE 0x00000001
#define SSINFO_FLAGS_PARTITION_ALIGNED_ON_DEVICE 0x00000002
#define SSINFO_FLAGS_NO_SEEK_PENALTY 0x00000004 /* SSD */
#define SSINFO_FLAGS_TRIM_ENABLED 0x00000008
/* sector size info struct for new level 11 Query FS Info */
struct smb3_fs_ss_info {
__le32 LogicalBytesPerSector;
__le32 PhysicalBytesPerSectorForAtomicity;
__le32 PhysicalBytesPerSectorForPerf;
__le32 FileSystemEffectivePhysicalBytesPerSectorForAtomicity;
__le32 Flags;
__le32 ByteOffsetForSectorAlignment;
__le32 ByteOffsetForPartitionAlignment;
}
--
Thanks,
Steve
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