master dd79a50 1/2: Fix documentation of a recent change

[Eli Zaretskii]

branch: master
commit dd79a5050a9f3b37a663c8bcd64f228d0e8711d2
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Fix documentation of a recent change
    
    * src/process.c (syms_of_process) <process-prioritize-lower-fds>:
    Doc fix.
    
    * etc/NEWS: Reword the entry for 'process-prioritize-lower-fds'.
---
 etc/NEWS      | 12 +++++++-----
 src/process.c | 11 +++++++----
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 7f9bf5c..ea74dfe 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2706,11 +2706,13 @@ the Emacs Lisp reference manual for background.
 * Lisp Changes in Emacs 28.1
 
 ---
-** New variable 'process-prioritize-lower-fds'.
-When looping through file descriptors to handle subprocess output, try
-to continue from where the previous loop left off instead of always
-beginning from file descriptor zero.  Set this variable to t to get
-the old behaviour.
+** Emacs now attempts to test for high-rate subprocess output more fairly.
+When several subprocesses produce output simultaneously at high rate,
+Emacs will now by default attempt to service them all in a round-robin
+fashion.  Set the new variable 'process-prioritize-lower-fds' to a
+non-nil value to get back the old behavior, whereby after reading
+from a subprocess, Emacs would check for output of other subprocesses
+in a way that is likely to read from the same process again.
 
 +++
 ** New function 'sxhash-equal-including-properties'.
diff --git a/src/process.c b/src/process.c
index 2f32ead..c354f3a 100644
--- a/src/process.c
+++ b/src/process.c
@@ -8495,10 +8495,13 @@ The variable takes effect when `start-process' is 
called.  */);
   Vprocess_adaptive_read_buffering = Qt;
 
   DEFVAR_BOOL ("process-prioritize-lower-fds", process_prioritize_lower_fds,
-              doc: /* If nil, try to not prioritize reading from any specific 
process.
-Emacs loops through file descriptors to receive data from subprocesses.  After
-accepting output from the first file descriptor with available data, restart 
the
-loop from the file descriptor 0 if this option is non-nil.  */);
+              doc: /* Whether to start checking for subprocess output from 
first file descriptor.
+Emacs loops through file descriptors to check for output from subprocesses.
+If this variable is nil, the default, then after accepting output from a
+subprocess, Emacs will continue checking the rest of descriptors, starting
+from the one following the descriptor it just read.  If this variable is
+non-nil, Emacs will always restart the loop from the first file descriptor,
+thus favoring processes with lower descriptors.  */);
   process_prioritize_lower_fds = 0;
 
   DEFVAR_LISP ("interrupt-process-functions", Vinterrupt_process_functions,