> On Nov 21, 2015, at 10:12, Z Zhang <zhangz.da...@outlook.com> wrote:
> 
> Hi Guys,
> 
> Now we have a very small cluster with 3 OSDs but using 40Gb NIC. We use 
> ceph-fuse as cephfs client and enable readahead, but testing single reading a 
> large file from cephfs via fio, dd or cp can only achieve ~70+MB/s, even if 
> fio or dd's block size is set to 1MB or 4MB.
> 
> From the ceph client log, we found each read request's size (ll_read) is 
> limited to 128KB, which should be the limitation of kernel fuse's 
> FUSE_MAX_PAGES_PER_REQ = 32. We may try to increase this value to see the 
> performance difference, but are there other options we can try to increase 
> single read performance?
> 

try setting client_readahead_max_bytes to 4M

Yan, Zheng                                        

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