Date: Sun, 14 Aug 2016 22:21:48 +0200 From: Ben RUBSON <ben.rubson@gmail.com> To: freebsd-fs@freebsd.org Subject: Re: [iSCSI] Trying to reach max disk throughput Message-ID: <A28531DD-65FC-4CE0-A40F-CF9B569C3AEB@gmail.com> In-Reply-To: <7CE3E62B-8251-4390-BD90-CF2F76F57CA7@gmail.com> References: <6B32251D-49B4-4E61-A5E8-08013B15C82B@gmail.com> <20160810114404.GA80485@brick> <7CE3E62B-8251-4390-BD90-CF2F76F57CA7@gmail.com>
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> On 10 Aug 2016, at 15:27, Ben RUBSON <ben.rubson@gmail.com> wrote: >=20 >>=20 >> On 10 Aug 2016, at 13:44, Edward Tomasz Napiera=C5=82a = <trasz@FreeBSD.org> wrote: >>=20 >> On 0810T1154, Ben RUBSON wrote: >>> Hello, >>>=20 >>> I'm facing something strange with iSCSI, I can't manage to reach the = expected disk throughput using one (read or write) thread. >>=20 >> [..] >>=20 >>> ### Initiator : iscsi disk throughput : >>>=20 >>> ## dd if=3D/dev/da8 of=3D/dev/null bs=3D$((128*1024)) count=3D81920 >>> 10737418240 bytes transferred in 34.731815 secs (309152234 = bytes/sec) - 295MB/s >>>=20 >>> With 2 parallel dd jobs : 345MB/s >>> With 4 parallel dd jobs : 502MB/s >>>=20 >>>=20 >>>=20 >>> ### Questions : >>>=20 >>> Why such a difference ? >>> Where are the 167MB/s (462-295) lost ? >>=20 >> Network delays, I suppose. >=20 > I just saw that iSER is available in FreeBSD 11, let's install BETA4 = and give it a try. OK, as a target I used Linux TGT, as iSER target (isert) is not FreeBSD = available yet. ### Target : local disk throughput, one thread : # dd if=3D/dev/da8 of=3D/dev/null bs=3D$((128*1024)) count=3D81920 10737418240 bytes (11 GB) copied, 21.3898 s, 502 MB/s ### Initiator : iscsi disk throughput, one thread : # dd if=3D/dev/da8 of=3D/dev/null bs=3D$((128*1024)) count=3D81920 10737418240 bytes transferred in 34.938676 secs (307321843 bytes/sec) - = 293 MB/s ### Initiator : iSER disk throughput, one thread : # dd if=3D/dev/da8 of=3D/dev/null bs=3D$((128*1024)) count=3D81920 10737418240 bytes transferred in 20.371947 secs (527068838 bytes/sec) - = 502 MB/s No need to comment, let's wait for the FreeBSD iSER target then ! Ben
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