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author | joe <joe@FreeBSD.org> | 2002-02-05 21:32:57 +0000 |
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committer | joe <joe@FreeBSD.org> | 2002-02-05 21:32:57 +0000 |
commit | 39b59a2a202dece886ca3761c3237e00c694b3e2 (patch) | |
tree | 7df3bf3a5e341f98da51d8b8349f1b90b4914895 /share/man/man9/physio.9 | |
parent | 95a4ae283045827d7b72aa026dbcc7bf9ff6745a (diff) | |
download | FreeBSD-src-39b59a2a202dece886ca3761c3237e00c694b3e2.zip FreeBSD-src-39b59a2a202dece886ca3761c3237e00c694b3e2.tar.gz |
Update the physio man page to better reflect reality.
PR: docs/30603
Reviewed by: phk
MFC after: 3 days
Diffstat (limited to 'share/man/man9/physio.9')
-rw-r--r-- | share/man/man9/physio.9 | 51 |
1 files changed, 14 insertions, 37 deletions
diff --git a/share/man/man9/physio.9 b/share/man/man9/physio.9 index 9e9eeda..add4c64 100644 --- a/share/man/man9/physio.9 +++ b/share/man/man9/physio.9 @@ -54,16 +54,12 @@ The .Fn physio is a helper function typically called from character device read and write routines to start I/O on a user process buffer. -It calls back on the -provided -.Fa strategy -routine one or more times to complete the transfer described by -.Fa uio . -The maximum amount of data to transfer with each call to -.Fa strategy -is determined by the -.Fa minphys -routine. +The maximum amount of data to transfer with each call +is determined by: +.Bd -literal +dev->si_iosize_max +.Ed +.Pp Since .Fa uio normally describes user space addresses, @@ -74,38 +70,11 @@ flag on the process. .Fn physio always awaits the completion of the entire requested transfer before returning, unless an error condition is detected earlier. -In all cases, -the buffer passed in -.Fa bp -is locked (marked as -.Dq busy ) -for the duration of the entire transfer. .Pp A break-down of the arguments follows: .Bl -tag -width indent -.It Fa strategy -The device strategy routine to call for each chunk of data to initiate -device I/O. -.It Fa bp -The buffer to use with the strategy routine. -The buffer flags will have -.Dv B_BUSY , -and -.Dv B_PHYS -set when passed to the strategy routine. -If -.Dv NULL , -a buffer is allocated from a system pool. .It Fa dev The device number identifying the device to interact with. -.It Fa flags -Direction of transfer; the only valid settings are -.Dv B_READ -or -.Dv B_WRITE . -.It Fa minphys -A device specific routine called to determine the maximum transfer size -that the device's strategy routine can handle. .It Fa uio The description of the entire transfer as requested by the user process. Currently, the results of passing a @@ -139,3 +108,11 @@ condition. .Sh SEE ALSO .Xr read 2 , .Xr write 2 +.Sh HISTORY +The +.Xr physio 9 +manual page is originally from NetBSD with minor changes for applicability +with FreeBSD. +.Pp +The physio(9) call has been completely re-written for providing higher +I/O performance, and better paging performance. |