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Message-ID: <8255.1242827906@jrobl> Date: Wed, 20 May 2009 22:58:26 +0900 From: hooanon05@...oo.co.jp To: Marcin Krol <mrkafk@...il.com> Cc: linux-kernel@...r.kernel.org Subject: Re: inotify limits - thousands (tens of thousands?) of watches Marcin Krol: > I'm not a kernel programmer, but I want to develop a program that would > watch modifications in *all* user directories on a busy server using > inotify. ::: > 1. is it safe? that is, will it not lock the kernel up, or cause > excessive memory consumption? > > 2. is it economic in terms of CPU time and RAM? I have no idea how to > even measure such a thing happening in the kernel.. The maximum number of inotify instances per user is limited to /proc/sys/fs/inotify/max_user_instances which is 128 by default. And also the number of watches per user is limited by /proc/sys/fs/inotify/max_user_watches (8192 by defaut). Theoretically you may be able to monitor 8192 directories, but it consumes memory. If periodical rsync is out of question for you, how about kprobe? While I don't think it is a beautiful solution, to set a hook to vfs_mkdir, vfs_unlink, etc and to compare the target super_block may work for you. See Documentation/kprobe.txt in detail. J. R. Okajima -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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