Date: Sun, 2 Nov 2003 21:20:10 -0800 From: David Schultz <das@FreeBSD.ORG> To: Vivek Pai <vivek@CS.Princeton.EDU> Cc: "=?us-ascii@FreeBSD.ORG"@FreeBSD.ORG Subject: Re: Some mmap observations compared to Linux 2.6/OpenBSD Message-ID: <20031103052010.GA71583@VARK.homeunix.com> In-Reply-To: <3FA2C63C.5000900@cs.princeton.edu> References: <1066789354.21430.39.camel@boxster.onthenet.com.au> <20031022082953.GA69506@rot13.obsecurity.org> <1066816287.25609.34.camel@boxster.onthenet.com.au> <20031022095754.GA70026@rot13.obsecurity.org> <1066820436.25609.93.camel@boxster.onthenet.com.au> <xzpk76sc425.fsf@dwp.des.no> <20031026052854.GA20701@VARK.homeunix.com> <3FA2C63C.5000900@cs.princeton.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, Oct 31, 2003, Vivek Pai wrote: > Take a look at Figure 6, page 9 in the following: > http://www.cs.princeton.edu/~yruan/DeBox/debox.pdf > > On a 1GHz box with 1GB of memory, we were spending > 4-5 milliseconds per mmap call, and that was limiting > the throughput of our server on SpecWeb99. > > Figure 9 on page 11 shows that just getting rid of the > mmap/munmap/mincore calls in this server got us a 50% > performance boost on a fairly complicated workload. The > SpecWeb99 workload was modeled after several web sites, > so this might actually be a performance problem in the > real world. > > If you look at figure 11, page 12, you'll see that with > various improvements, our server's median latency dropped to > less than 1ms. An mmap time of several milliseconds would > kill that benefit. Okay, I guess SpecWeb99 is ``real world'' enough for me to justify the assertion that there is an mmap() performance problem. Just out of curiosity, how many regions did SpecWeb99 map? (i.e. what does 'dd if=/proc/$pid/map bs=64k count=1 | wc -l' give?)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20031103052010.GA71583>