Messages in this thread | | | Date | Fri, 10 Feb 2017 12:53:52 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86, locking: Inline *_unlock_bh & *_unlock_irqrestore |
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On Thu, 2 Feb 2017, Waiman Long wrote:
> For spinlock and read-write locks, both *_unlock() and *_unlock_irq() > functions are inlined if !PREEMPT. Whereas the *_unlock_bh() and > *unlock_irqrestore() are not inlined as that will increase the size > of the kernel binary. > > Given the fact that the PV qspinlock unlock call is a callee-saved > function pointer, the unlock function is essentially a leaf function > if !PREEMPT is true under all circumstances. Inlining it will enable > the compiler to do much better optimization around the the unlock > call sites. Similarly for the read-write locks. > > To unleash this additional performance, all these unlock functions > are now inlined for x86-64 kernel where kernel size is usually less > of a concern. For 32-bit kernel, it is assumed that the focus will > be a bit more on kernel size optimization and so those functions are > not inlined. > > With 4.9.6 kernel source and gcc 4.8.5-11 compiler, the text size > of the base vmlinux binary increased from 8527918 bytes to 8462235 > bytes. That was an increase of 0.78%.
Increased from 8527918 bytes to 8462235?
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