On Tue, 2019-12-31 at 15:23 +0100, Markus Elfring wrote: > … > > +++ b/fs/exfat/nls.c > … > > +int exfat_nls_cmp_uniname(struct super_block *sb, unsigned short *a, > > + unsigned short *b) > > +{ > > + int i; > > + > > + for (i = 0; i < MAX_NAME_LENGTH; i++, a++, b++) { > > + if (exfat_nls_upper(sb, *a) != exfat_nls_upper(sb, *b)) > > Can it matter to compare run time characteristics with the following > code variant? > > + for (i = 0; i < MAX_NAME_LENGTH; i++) { > + if (exfat_nls_upper(sb, a[i]) != exfat_nls_upper(sb, b[i])) Markus, try comparing the object code produced by the compiler first, it's likely identical. If this is actually a performance sensitive path, it might improve runtime by having 2 code paths to avoid the testing of sbi->options.case_sensitive for each u16 value in the array. Something like: (uncompiled, untested, written in email client) static inline unsigned short exfat_sbi_upper(struct exfat_sb_info *sbi, unsigned short a) { if (sbi->vol_utbl[a]) return sbi->vol_utbl[a]; return a; } int exfat_nls_cmp_uniname(struct super_block *sb, unsigned short *a, unsigned short *b) { int i; struct exfat_sb_info *sbi = EXFAT_SB(sb); if (!sbi->options.case_sensitive) { for (i = 0; i < MAX_NAME_LENGTH; i++, a++, b++) { if (exfat_sbi_upper(sbi, *a) != exfat_sbi_upper(sbi, *b)) return 1; if (*a == 0x0) return 0; } } else { for (i = 0; i < MAX_NAME_LENGTH; i++, a++, b++) { if (*a != *b) return 1; if (*a == 0x0) return 0; } } return 0; }