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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48317d3e245sm195442315e9.8.2026.02.07.02.51.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Feb 2026 02:51:32 -0800 (PST) Date: Sat, 7 Feb 2026 10:51:30 +0000 From: David Laight To: Giovanni Cabiddu , Herbert Xu , "David S. Miller" , Suman Kumar Chakraborty , Vijay Sundar Selvamani , George Abraham P , qat-linux@intel.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Marco Elver , Will Deacon , Peter Zijlstra Subject: Re: [PATCH next] crypto: qat - replace avg_array() with a better function Message-ID: <20260207105130.4af50ce1@pumpkin> In-Reply-To: <20260206210940.315817-1-david.laight.linux@gmail.com> References: <20260206210940.315817-1-david.laight.linux@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 6 Feb 2026 21:09:40 +0000 david.laight.linux@gmail.com wrote: Cc the people discussing unqual_scalar_typeof() for arm64 LTO READ_ONCE(). > From: David Laight > > avg_array() is defined as a 'type independant' #define. > However the algorithm is only valid for unsigned types and the > implementation is only valid for u64. > All the callers pass temporary kmalloc() allocated arrays of u64. > > Replace with a function that takes a pointer to a u64 array. > > Change the implementation to sum the low and high 32bits of each > value separately and then compute the average. > This will be massively faster as it does two divisions rather than > one for each element. > > Also removes some very pointless __unqual_scalar_typeof(). > They could be 'auto _x = 0 ? x + 0 : 0;' even if the types weren't fixed. > > Only compile tested. > > Signed-off-by: David Laight > --- > .../intel/qat/qat_common/adf_tl_debugfs.c | 38 ++++++++----------- > 1 file changed, 15 insertions(+), 23 deletions(-) > > diff --git a/drivers/crypto/intel/qat/qat_common/adf_tl_debugfs.c b/drivers/crypto/intel/qat/qat_common/adf_tl_debugfs.c > index b81f70576683..a084437a2631 100644 > --- a/drivers/crypto/intel/qat/qat_common/adf_tl_debugfs.c > +++ b/drivers/crypto/intel/qat/qat_common/adf_tl_debugfs.c > @@ -77,32 +77,24 @@ static int tl_collect_values_u64(struct adf_telemetry *telemetry, > * @len: Number of elements. > * > * This algorithm computes average of an array without running into overflow. > + * (Provided len is less than 2 << 31.) > * > * Return: average of values. > */ > -#define avg_array(array, len) ( \ > -{ \ > - typeof(&(array)[0]) _array = (array); \ > - __unqual_scalar_typeof(_array[0]) _x = 0; \ > - __unqual_scalar_typeof(_array[0]) _y = 0; \ > - __unqual_scalar_typeof(_array[0]) _a, _b; \ > - typeof(len) _len = (len); \ > - size_t _i; \ > - \ > - for (_i = 0; _i < _len; _i++) { \ > - _a = _array[_i]; \ > - _b = do_div(_a, _len); \ > - _x += _a; \ > - if (_y >= _len - _b) { \ > - _x++; \ > - _y -= _len - _b; \ > - } else { \ > - _y += _b; \ > - } \ > - } \ > - do_div(_y, _len); \ > - (_x + _y); \ > -}) > +static u64 avg_array(const u64 *array, size_t len) > +{ > + u64 sum_hi = 0, sum_lo = 0; > + size_t i; > + > + for (i = 0; i < len; i++) { > + sum_hi += array[i] >> 32; > + sum_lo += (u32)array[i]; > + } > + > + sum_lo += (u64)do_div(sum_hi, len) << 32; > + > + return (sum_hi << 32) + div_u64(sum_lo, len); > +} > > /* Calculation function for simple counter. */ > static int tl_calc_count(struct adf_telemetry *telemetry,