Date: Tue, 21 Mar 2006 18:26:45 -0500 From: Mikhail Teterin <mi+mx@aldan.algebra.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: alc@freebsd.org, stable@freebsd.org Subject: Re: more weird bugs with mmap-ing via NFS Message-ID: <200603211831.54172.mi%2Bmx@aldan.algebra.com> In-Reply-To: <200603212256.k2LMuHT0006842@apollo.backplane.com> References: <200603211607.30372.mi%2Bmx@aldan.algebra.com> <200603211747.36251.mi%2Bmx@aldan.algebra.com> <200603212256.k2LMuHT0006842@apollo.backplane.com>
next in thread | previous in thread | raw e-mail | index | archive | help
צ×ÔÏÒÏË 21 ÂÅÒÅÚÅÎØ 2006 17:56, Matthew Dillon ÷É ÎÁÐÉÓÁÌÉ: > šFor UDP mounts, 65536 is too large (the UDP data length can > š š only be 65536 bytes. šFor that matter, the *IP* packet itself can > š š not exceed 65535 bytes. šSo 65536 will not work with a UDP mount. Well, then the mount should fail with EINVALID or something, maybe, it just quietly reduces the size to the maximum? However, the problem is the same with 32K and 16K packets. You give good reasons for such sizes being slow, but this does not explain, why it does not work at all... > š š The second problem is related to the network driver. šThe packet MTU > š š is 1500, which means, typically, a limit of around 1460-1480 payload > š š bytes per packet. Yes, unfortunately, your 2004 patches, that allowed one to specify a different MTU for different hosts on the local network never made it to any tree :-( > š š I would stick to an NFS block size of 8K or 16K. šFrankly, there is > š š no real reason to use a larger block size. The problem is about same with 32K and 16K packets. With 8K packets, the thing kind-of works (although trying to `systat -vm' still stalls disk access), but the outgoing traffic is over 20Mb/s on average -- MUCH more, than the writing program itself generates. Thanks for your help. Yours, -mi
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200603211831.54172.mi%2Bmx>