Date: Wed, 07 Mar 2007 23:36:06 -0600 From: Eric Anderson <anderson@freebsd.org> To: Fluffles <etc@fluffles.net> Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@fer.hr>, freebsd-geom@freebsd.org Subject: Re: Some Unix benchmarks for those who are interesed Message-ID: <45EFA0C6.3060905@freebsd.org> In-Reply-To: <45EF9B8F.4000201@fluffles.net> References: <20070306020826.GA18228@nowhere> <45ECF00D.3070101@samsco.org><20070306050312.GA2437@nowhere><008101c75fcc$210c74a0$0c00a8c0@Artem> <esk9vq$uhh$1@sea.gmane.org><001a01c7601d$5d635ee0$0c00a8c0@Artem> <eskka8$adn$1@sea.gmane.org><001801c7603a$5339e020$0c00a8c0@Artem> <eskpd1$sm4$1@sea.gmane.org> <20070307105144.1d4a382f@daydream.goid.lan><002801c760e2$5cb5eb50$0c00a8c0@Artem> <esmvnp$khs$1@sea.gmane.org><005b01c760e6$9a798bf0$0c00a8c0@Artem> <esn2s6$1i9$1@sea.gmane.org> <001601c760ee$f76fa300$0c00a8c0@Artem> <45EF2252.1000202@fluffles.net> <45EF253B.8030909@fer.hr> <45EF9B8F.4000201@fluffles.net>
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On 03/07/07 23:13, Fluffles wrote: > Ivan Voras wrote: >> Fluffles wrote: >> >> >>> If you use dd on the raw device (meaning no UFS/VFS) there is no >>> read-ahead. This means that the following DD-command will give lower STR >>> read than the second: >>> >>> no read-ahead: >>> dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 >>> read-ahead and multiple I/O queue depth: >>> dd if=/mounted/mirror/volume of=/dev/null bs=1m count=1000 >>> >> I'd agree in theory, but bonnie++ gives WORSE results than raw device: >> > > On what hardware is this? Using any form of geom software RAID? > > The low Per Char results would lead me to believe it's a very slow CPU; > maybe VIA C3 or some old pentium? Modern systems should get 100MB/s+ in > per-char bonnie benchmark, even a Sempron 2600+ 1.6GHz 128KB cache which > costs about $39. Then it might be logical DD gets higher results since > this is more 'easy' to handle by the CPU. The VFS/UFS layer adds > potential for nice performance-increases but it does take it's toll in > the form of cputime overhead. If your CPU is very slow, i can imagine > these optimizations having a detrimental effect instead. Just guessing here. Before making speculative claims about slow CPU's and putting the VIA C3 in with that pile, please at least refer to what makes you believe that it is an issue. Comparing the VIA C3 to 'some old pentium' isn't exactly fair or accurate, and inferring it isn't a modern system isn't true either. Forgive me though, I'm biased. Eric
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