| Message ID | 1473067703-10746-1-git-send-email-thuth@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
On 05/09/16 19:28, Thomas Huth wrote: > When loading a file via the spapr-vlan network interface, SLOF > currently leaks quite a lot of memory, about 12kB each time. > This happens mainly because veth_init() uses for example > SLOF_alloc_mem_aligned(8192, 4096) and similar calls to get > the memory, but the space for the additional alignment is never > returned anymore later. An easy way to ease this situation is to > improve SLOF_alloc_mem_aligned() a little bit. We normally get memory > from SLOF_alloc_mem() which is aligned pretty well already, thanks to > the buddy allocator in SLOF. So we can try to first get a memory > block with the exact size first, and only do the alignment dance > if the first allocation was not aligned yet. > > Signed-off-by: Thomas Huth <thuth@redhat.com> I do not like it but since the allocated address does not store the size somewhere nearby, I'll apply this anyway, thanks. > --- > slof/helpers.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/slof/helpers.c b/slof/helpers.c > index 48c34a6..b049141 100644 > --- a/slof/helpers.c > +++ b/slof/helpers.c > @@ -69,9 +69,14 @@ void *SLOF_alloc_mem(long size) > > void *SLOF_alloc_mem_aligned(long size, long align) > { > - unsigned long addr = (unsigned long)SLOF_alloc_mem(size + align - 1); > - addr = addr + align - 1; > - addr = addr & ~(align - 1); > + unsigned long addr = (unsigned long)SLOF_alloc_mem(size); > + > + if (addr % align) { > + SLOF_free_mem((void *)addr, size); > + addr = (unsigned long)SLOF_alloc_mem(size + align - 1); > + addr = addr + align - 1; > + addr = addr & ~(align - 1); > + } > > return (void *)addr; > } >
On 14/09/16 15:39, Alexey Kardashevskiy wrote: > On 05/09/16 19:28, Thomas Huth wrote: >> When loading a file via the spapr-vlan network interface, SLOF >> currently leaks quite a lot of memory, about 12kB each time. >> This happens mainly because veth_init() uses for example >> SLOF_alloc_mem_aligned(8192, 4096) and similar calls to get >> the memory, but the space for the additional alignment is never >> returned anymore later. An easy way to ease this situation is to >> improve SLOF_alloc_mem_aligned() a little bit. We normally get memory >> from SLOF_alloc_mem() which is aligned pretty well already, thanks to >> the buddy allocator in SLOF. So we can try to first get a memory >> block with the exact size first, and only do the alignment dance >> if the first allocation was not aligned yet. >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> > > I do not like it but since the allocated address does not store the size > somewhere nearby, I'll apply this anyway, thanks. I asked for advice and we could actually always try allocating (size+align-1) here, and then if the address is not aligned - free the chunk before aligned address, if aligned - free the chunk after addr+size. > > >> --- >> slof/helpers.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/slof/helpers.c b/slof/helpers.c >> index 48c34a6..b049141 100644 >> --- a/slof/helpers.c >> +++ b/slof/helpers.c >> @@ -69,9 +69,14 @@ void *SLOF_alloc_mem(long size) >> >> void *SLOF_alloc_mem_aligned(long size, long align) >> { >> - unsigned long addr = (unsigned long)SLOF_alloc_mem(size + align - 1); >> - addr = addr + align - 1; >> - addr = addr & ~(align - 1); >> + unsigned long addr = (unsigned long)SLOF_alloc_mem(size); >> + >> + if (addr % align) { >> + SLOF_free_mem((void *)addr, size); >> + addr = (unsigned long)SLOF_alloc_mem(size + align - 1); >> + addr = addr + align - 1; >> + addr = addr & ~(align - 1); >> + } >> >> return (void *)addr; >> } >> > >
On 15.09.2016 05:49, Alexey Kardashevskiy wrote: > On 14/09/16 15:39, Alexey Kardashevskiy wrote: >> On 05/09/16 19:28, Thomas Huth wrote: >>> When loading a file via the spapr-vlan network interface, SLOF >>> currently leaks quite a lot of memory, about 12kB each time. >>> This happens mainly because veth_init() uses for example >>> SLOF_alloc_mem_aligned(8192, 4096) and similar calls to get >>> the memory, but the space for the additional alignment is never >>> returned anymore later. An easy way to ease this situation is to >>> improve SLOF_alloc_mem_aligned() a little bit. We normally get memory >>> from SLOF_alloc_mem() which is aligned pretty well already, thanks to >>> the buddy allocator in SLOF. So we can try to first get a memory >>> block with the exact size first, and only do the alignment dance >>> if the first allocation was not aligned yet. >>> >>> Signed-off-by: Thomas Huth <thuth@redhat.com> >> >> I do not like it but since the allocated address does not store the size >> somewhere nearby, I'll apply this anyway, thanks. > > I asked for advice and we could actually always try allocating > (size+align-1) here, and then if the address is not aligned - free the > chunk before aligned address, if aligned - free the chunk after addr+size. That could work ... but you should also be prepared that you might need to free chunks on both ends of the allocation, e.g. when somebody asks for a region with "align" being much bigger than "size"... Thomas
diff --git a/slof/helpers.c b/slof/helpers.c index 48c34a6..b049141 100644 --- a/slof/helpers.c +++ b/slof/helpers.c @@ -69,9 +69,14 @@ void *SLOF_alloc_mem(long size) void *SLOF_alloc_mem_aligned(long size, long align) { - unsigned long addr = (unsigned long)SLOF_alloc_mem(size + align - 1); - addr = addr + align - 1; - addr = addr & ~(align - 1); + unsigned long addr = (unsigned long)SLOF_alloc_mem(size); + + if (addr % align) { + SLOF_free_mem((void *)addr, size); + addr = (unsigned long)SLOF_alloc_mem(size + align - 1); + addr = addr + align - 1; + addr = addr & ~(align - 1); + } return (void *)addr; }
When loading a file via the spapr-vlan network interface, SLOF currently leaks quite a lot of memory, about 12kB each time. This happens mainly because veth_init() uses for example SLOF_alloc_mem_aligned(8192, 4096) and similar calls to get the memory, but the space for the additional alignment is never returned anymore later. An easy way to ease this situation is to improve SLOF_alloc_mem_aligned() a little bit. We normally get memory from SLOF_alloc_mem() which is aligned pretty well already, thanks to the buddy allocator in SLOF. So we can try to first get a memory block with the exact size first, and only do the alignment dance if the first allocation was not aligned yet. Signed-off-by: Thomas Huth <thuth@redhat.com> --- slof/helpers.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)