Verifying your install

php -m | grep turbovec

A deeper check that exercises construction, add, and search:

php -r '
$i = new Displace\Vector\TurboQuantIndex(8);
$i->add(pack("g*", 1,0,0,0,0,0,0,0));
$r = $i->search(pack("g*", 1,0,0,0,0,0,0,0), 1);
echo $r->ids()[0] === 0 ? "ext-turbovec OK\n" : "unexpected result\n";
'

Troubleshooting

libopenblas.so.0: cannot open shared object file (Linux) — install the OpenBLAS runtime: sudo apt install libopenblas0 (Debian/Ubuntu) or your distro’s equivalent.

undefined symbol errors at load — the binary was built for a different PHP minor. PIE matches automatically; for source builds, rebuild against the php-config of the PHP that’s loading it.

extension_loaded('turbovec') is false but no error — check which ini PHP is reading (php --ini) and that the extension= line points at an absolute path.

Old/exotic x86 CPU — pre-Haswell (2013) processors run the scalar fallback. Results are identical; throughput is lower. Nothing to configure — kernel selection is automatic at runtime.