Date: Fri, 30 Dec 2016 21:58:49 -0500 From: Shea Levy <shea@shealevy.com> To: freebsd-hackers@freebsd.org Subject: Detecting changes when mapping /dev/devstat Message-ID: <87r34o3ity.fsf@shlevy-laptop.i-did-not-set--mail-host-address--so-tickle-me>
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--=-=-= Content-Type: text/plain Hi all, What is the appropriate way to detect changes when accessing devstat info via a mapping of /dev/devstat? I'm interested both in changes to the device list as a whole and new statistics on a given device. For new stats on a given device, it seems the only way to detect a new stat is to check the sequence number for that device. Is that right? For changes in the device list, it's a bit less clear. My hope was that I could map space for one more struct devstat than the current numdevs and just check to see if some field or other is nonzero, but in my glances through subr_devstat.c I'm not sure if there are any guarantees about those fields for structures past the current list, especially if a device was added and removed. Is there anything doable here? Thanks, Shea P.S. I wasn't quite sure which list was appropriate for this question, please feel free to point me to another! --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE6ESKvwKkwnxgMLnaXAvWlX2G/icFAlhnHukACgkQXAvWlX2G /icRQw//QqWGAy+nTglYUMMP1H9/JD+UHlFj3bbewU+yGELA/boVHauAqT53VmiE qbYr0W+d7lc0NgkUSVJzTOZfcxMKFqAuGZu3B/u3FVf1fif7VqBu80egqYmt2AaG FKrRfOUA/y6MJq0SRfNUCLeia7BIbaUMLOiqzWcmRZH7p0Tl9V4ZzhKq6sADWKEg 6BOKN9DN2U4v/4ZYtom9jZwKpecf/Vzp4rdCeweAi1cVuTlHul7QFk36lBKQJhhb +5zrFsiJfmVpxnZgHM9gXLlGotm+EB70tBzvKcUFe27MZx3L6gZOiz3zUpXsWm88 RZWX5F3p+A6TxhxcROnvsbKTCots/2vZYzhfufYhsyF12Kr2om9c4T+W201il1gv d9HNpjMjBHM0oHLAHEo3GVVlkWVHu4RdxJ08tTlMGlrmfdXhks/nbOk/1jk3QfNJ pLs+CvihnO7iYGzF4Llyp+sCpJJRh1GH53fs71260qJidtVgSjKXbMQsI4upoqLr fhorfPHvxiG0flOXOH3ngJMMgLuNOtMsIXIKP59ypj6f5kLEe+cDAY9JDNFjrnRv D4H5pZx3rQtMdMrdsnU8Xk+lmxu+/GwXn57TXzb1orxGpA5sJBtPDeanq7UJqEoc VhN6E53YC5epiCiKbL0/yzePOUf5WYgiFEU7PmBRYxDyuvBOXTc= =OEO6 -----END PGP SIGNATURE----- --=-=-=--
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