Date: Fri, 25 Oct 2013 23:59:05 +0800 (SGT) From: Patrick Dung <patrick_dkt@yahoo.com.hk> To: freebsd hackers <freebsd-hackers@freebsd.org> Subject: Strange write speed between /file and /tmp/file (may be related to 4k advanced format) Message-ID: <1382716745.90609.YahooMailNeo@web193506.mail.sg3.yahoo.com>
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Hi , I have asked the question in freebsd-questions but can't get reply so I tried to ask here first before submitting a bug report. I have a FreeBSD 9.2 64 bit installed in a VM. The host is Windows 7 with vmware workstation, the host is using an advanced format (4k) harddisk. I have noticed there is strange write speed between /file and /tmp/file. /dev/da0p3 is UFS2 created by default installer. I am thinking if the problem is caused by disk alignment. da0p3 starting sector is 786594, which seems not aligned by 4k (786594 *512/4096=98324.25) The dd result is repeatable. [root@testing2 /]# df -P Filesystem 512-blocks Used Avail Capacity Mounted on /dev/da0p3 6518712 4621000 1376216 77% / devfs 2 2 0 100% /dev fdescfs 2 2 0 100% /dev/fd procfs 8 8 0 100% /proc host:hgfs 591368064 405571456 185796608 69% /mnt-hgfs [root@testing2 /]# gpart show da0 => 34 7548861 da0 GPT (3.6G) 34 128 1 freebsd-boot (64k) 162 786432 2 freebsd-swap (384M) 786594 6760448 3 freebsd-ufs (3.2G) 7547042 1853 - free - (926k) [root@testing2 /]# dd if=/dev/zero of=/tmp/file bs=50M count=4 4+0 records in 4+0 records out 209715200 bytes transferred in 10.303288 secs (20354202 bytes/sec) [root@testing2 /]# rm /tmp/file [root@testing2 /]# dd if=/dev/zero of=/tmp/file bs=50M count=4 4+0 records in 4+0 records out 209715200 bytes transferred in 9.789672 secs (21422087 bytes/sec) [root@testing2 /]# rm /tmp/file [root@testing2 /]# ~^C [root@testing2 /]# dd if=/dev/zero of=/file bs=50M count=4 4+0 records in 4+0 records out 209715200 bytes transferred in 6.826694 secs (30719877 bytes/sec) [root@testing2 /]# rm /file [root@testing2 /]# dd if=/dev/zero of=/file bs=50M count=4 4+0 records in 4+0 records out 209715200 bytes transferred in 6.955417 secs (30151348 bytes/sec) [root@testing2 /]# rm /file Thanks and regards,Patrick Dung
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