Date: Wed, 25 May 2005 12:41:48 -0400 From: Sven Willenberger <sven@dmv.com> To: freebsd-stable@freebsd.org Subject: BKVASIZE for large block-size filesystems Message-ID: <1117039308.13175.48.camel@lanshark.dmv.com>
next in thread | raw e-mail | index | archive | help
FreeBSD5.4-Stable amd64 on a dual-opteron system with LSI-Megaraid 400G+ partion. The filesystem was created with: newfs -b 65536 -f 8192 -e 15835 /dev/amrd2s1d This is the data filesystem for a PostgreSQL database; as the default page size (files) is 8k, the above newfs scheme has 8k fragments which should fit nicely with the PostgreSQL page size. Now by default param.h defines BKVASIZE as 16384 (which has been pointed out in other posts as being *not* twice the default blocksize of 16k). I have modified it to be set at 32768 but still see a high and increasing value of vfs.bufdefragcnt which makes sense given the blocksize of the major filesystem in use. My question is are there any caveats about increasing BKVASIZE to 65536? The system has 8G of RAM and I understand that nbufs decreases with increasing BKVASIZE; how can I either determine if the resulting nbufs will be sufficient or calculate what is needed based on RAM and system usage? Also, will increasing BKVASIZE require a complete make buildworld or, if not, how can I remake the portions of system affected by BKVASIZE? Sven
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1117039308.13175.48.camel>