> -----Original Message----- > From: fio-owner@xxxxxxxxxxxxxxx [mailto:fio-owner@xxxxxxxxxxxxxxx] On > Behalf Of Jens Axboe > Sent: Tuesday, March 17, 2015 4:56 PM > To: Urs Schaltegger; fio@xxxxxxxxxxxxxxx > Subject: Re: fio always writes null bytes whatever I do > > On 03/12/2015 08:32 AM, Urs Schaltegger wrote: > > fio always writes null bytes whatever I do. I need random data to avoid > interference of deduplication solutions (within SSDs or using ZFS). > > ... > > Hmm yes, that looks like a regression. Does the attached work? > > > -- > Jens Axboe With this change, fio now defaults to spending a lot of time during writes in: get_io_u -> small_content_scramble (inlined) For example, doing writes to a pmem device, perf top shows the CPU time as: * 67% pmem memcpy * 21% fio get_io_u That disappears if you add zero_buffers since the initialization only happens once: * 89% pmem memcpy * ... * 0.02% fio get_io_u but that means a zero pattern is used, which may be too easy for some deduplicating storage devices to handle. --- Robert Elliott, HP Server Storage ��.n��������+%������w��{.n�������^n�r������&��z�ޗ�zf���h���~����������_��+v���)ߣ�
