Chaning the prctl() settings only affects the process (or thread) where prctl() is called and not the rest of processes running on the system.
Therefore running a timed "make check" on pre-compiled test binaries with suppressed output, possibly on an unloaded system, is a meaningful performance loss measure. Please note that Level 1 Data Cache flushing is disabled by default and the third prctl() call in this patch is just a placeholder. Guido On Sat, 05/07/2025 at 14.37 +0300, Jussi Kivilinna wrote: > On 14/06/2025 15:47, Guido Trentalancia via Gcrypt-devel wrote: > > Three runs of timed "make check" (with suppressed output) on > > libgcrypt > > version 1.11.1, with and without the safety feature enabled, > > provide > > the following meaningful results: > > > > safe (avg): 54.26 seconds > > > > unsafe (avg): 52.94 seconds > > > > Therefore, the performance loss of safe versus unsafe is 2.5%. > > Seems high given that "make check" is mostly single threaded test > code > running mostly in user-space and checking libgcrypt implementation. > > Changing these prctl settings will affect the application where > libgcrypt > was loaded (directly or indirectly) and can also affect performance > of other processes running on system (see discussion & push back on > L1d flush change in linux kernel). > > -Jussi > _______________________________________________ Gcrypt-devel mailing list Gcrypt-devel@gnupg.org https://lists.gnupg.org/mailman/listinfo/gcrypt-devel
