Date: Fri, 23 Apr 2010 00:59:28 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: freebsd-geom@FreeBSD.org Subject: d_maxsize .. si_iosize_max Message-ID: <4BD0C6C0.30008@icyb.net.ua>
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I see that many disk drivers are careful to set an optimal value for d_maxsize. On the other hand, si_iosize_max is hardcoded to MAXPHYS in geom_dev.c, which leads to suboptimal I/O for devices with actual maximum I/O size less than MAXPHYS. And right now d_maxsize seems to be used only for dumperinfo.maxiosize, which is a waste. So, perhaps, d_maxsize should be passed up through GEOM layer as a provider property, e.g. pp->maxiosize. So that si_iosize_max could be set correctly. Or, more importantly, so that final consumers (e.g. filesystems) could now correct optimal I/O size. Perhaps, this should even be split into max_read_size and max_write_size for geoms like gmirror where reads can be done in parallel. -- Andriy Gapon
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