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OPTIM: poll: optimize fd management functions for low register count CPUs

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Looking at the assembly code that updt_fd() and alloc/release_spec_entry
produce in the polling loops, it's clear that gcc has to recompute pointers
several times in a row because of limited spare registers. By better
grouping adjacent structure updates, we improve the code size by around
60 bytes in the fast path on x86.
This commit is contained in:
Willy Tarreau 2012-12-13 23:34:18 +01:00
parent 462c7206bc
commit 4a29144591
1 changed files with 4 additions and 3 deletions
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7
include/proto/fd.h
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@ -89,8 +89,8 @@ static inline void updt_fd(const int fd)
if (fdtab[fd].updated) if (fdtab[fd].updated)
/* already scheduled for update */ /* already scheduled for update */
return; return;
fd_updt[fd_nbupdt++] = fd;
fdtab[fd].updated = 1; fdtab[fd].updated = 1;
fd_updt[fd_nbupdt++] = fd;
} }
@ -100,8 +100,9 @@ static inline void alloc_spec_entry(const int fd)
if (fdtab[fd].spec_p) if (fdtab[fd].spec_p)
/* FD already in speculative I/O list */ /* FD already in speculative I/O list */
return; return;
fd_spec[fd_nbspec++] = fd; fd_nbspec++;
fdtab[fd].spec_p = fd_nbspec; fdtab[fd].spec_p = fd_nbspec;
fd_spec[fd_nbspec-1] = fd;
} }
/* Removes entry used by fd <fd> from the spec list and replaces it with the /* Removes entry used by fd <fd> from the spec list and replaces it with the
@ -117,7 +118,7 @@ static inline void release_spec_entry(int fd)
return; return;
fdtab[fd].spec_p = 0; fdtab[fd].spec_p = 0;
fd_nbspec--; fd_nbspec--;
if (pos <= fd_nbspec) { if (likely(pos <= fd_nbspec)) {
/* was not the last entry */ /* was not the last entry */
fd = fd_spec[fd_nbspec]; fd = fd_spec[fd_nbspec];
fd_spec[pos - 1] = fd; fd_spec[pos - 1] = fd;