bdflush - start, flush, or tune buffer-dirty-flush daemon
int bdflush(int func, long *address);
int bdflush(int func, long data);
: Since Linux 2.6, this system call is deprecated and does nothing.
It is likely to disappear altogether in a future kernel release. Nowadays, the
task performed by bdflush
() is handled by the kernel pdflush
() starts, flushes, or tunes the buffer-dirty-flush daemon. Only a
privileged process (one with the CAP_SYS_ADMIN
capability) may call
is negative or 0, and no daemon has been started, then
() enters the daemon code and never returns.
is 1, some dirty buffers are written to disk.
is 2 or more and is even (low bit is 0), then address
the address of a long word, and the tuning parameter numbered
-2)/2 is returned to the caller in that address.
is 3 or more and is odd (low bit is 1), then data
long word, and the kernel sets tuning parameter numbered (func
The set of parameters, their values, and their valid ranges are defined in the
Linux kernel source file fs/buffer.c
is negative or 0 and the daemon successfully starts,
() never returns. Otherwise, the return value is 0 on success
and -1 on failure, with errno
set to indicate the error.
- An attempt was made to enter the daemon code after another
process has already entered.
- address points outside your accessible address
- An attempt was made to read or write an invalid parameter
number, or to write an invalid value to a parameter.
- Caller does not have the CAP_SYS_ADMIN
Since version 2.23, glibc no longer supports this obsolete system call.
() is Linux-specific and should not be used in programs intended
to be portable.
This page is part of release 4.16 of the Linux man-pages
description of the project, information about reporting bugs, and the latest
version of this page, can be found at