inline

[Alejandro Colomar]

On 6/2/22 01:49, Alejandro Colomar wrote:
> I'm concerned that we may be inlining too much.
> 
> 
> See for example the following function calls:
> 
> $ grep -rnA1 nxt_slow_path | grep -B1 nxt_thread_get_tid
> src/nxt_thread.c:247:    if (nxt_slow_path(thr->tid == 0)) {
> src/nxt_thread.c-248-        thr->tid = nxt_thread_get_tid();
> -- 
> src/nxt_thread.c:257:        if (nxt_slow_path(thr->tid == 0)) {
> src/nxt_thread.c-258-            thr->tid = nxt_thread_get_tid();
> 
> 
> Looks good, but then see the definition of nxt_thread_get_tid() (it has 
> several difinitions, one for each system, but I'll copy here one that is 
> pretty big (NXT_AIX)):
> 
> 
[...]
> 
> 
> We're inlining a *huge* function in some cases where we know it's a slow 
> path.  We could do better by marking the function as inline (without 
> [[gnu::always_inline]]), and let the compiler decide that it doesn't 
> want to inline when it's in an `nxt_slow_path()`.
> 

I found the following functions that are being inlined within 
nxt_slow_path(), which seems wrong:


$ find src \
   | grep '\.[ch]$' \
   | xargs pcregrep -M '(?s)nxt(_always)?_inline[\s\w\*]*\s\*?\w+\(' \
   | grep -o '\w\+(' \
   | sed 's/(//' \
   | while read f; do
	find src \
	| grep '\.[ch]$' \
	| xargs pcregrep -Mn 
'(?s)^(\s+)[^\n]*nxt_slow_path(?:(?!^\1?}).)*?\b'"$f"'\b(?:(?!\1}).)*?^\1}' 
\
	| sed -E 's/^[^:]+:[0-9]+:/\n\n&\n/' \
	| grep -o "\b$f\b";
	# You can filter with the following instead of `grep -o ...`
	# to view the code (remember to remove |sort|uniq):
	# | perl -pe 's/('"$f"')/\033[32m\1\033[0m/';
   done \
   | sort \
   | uniq;
nxt_array_init
nxt_array_remove_last
nxt_buf_cpystr
nxt_buf_dummy_completion
nxt_cpymem
nxt_fastcgi_param_length
nxt_h1p_request_error
nxt_http_date
nxt_mp_chunk_pages_index
nxt_next_highest_power_of_two
nxt_perl_psgi_add_sptr
nxt_perl_psgi_add_str
nxt_perl_psgi_add_value
nxt_perl_psgi_cb_request_done
nxt_pivot_root
nxt_port_close_fds
nxt_port_mmap_chunk_id
nxt_port_mmap_chunk_start
nxt_port_mmap_set_chunk_free
nxt_port_rpc_lhq_peer
nxt_port_socket_write
nxt_thread_event_engine
nxt_thread_get_tid
nxt_unit_close
nxt_unit_mmap_buf_insert
nxt_unit_process_release



These functions should not be forced to be inline (except oneliners).


Cheers,

Alex

-- 
Alejandro Colomar
<http://www.alejandro-colomar.es/>
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