Re: [Qemu-devel] [PATCH v4 25/26] tcg: Check for overflow via highwater mark

2015-10-01 Thread Peter Maydell
On 30 September 2015 at 17:50, Aurelien Jarno wrote: > On 2015-09-30 15:09, Richard Henderson wrote: >> We currently pre-compute an worst case code size for any TB, which >> works out to be 122kB. Since the average TB size is near 1kB, this >> wastes quite a lot of storage.

Re: [Qemu-devel] [PATCH v4 25/26] tcg: Check for overflow via highwater mark

2015-10-01 Thread Richard Henderson
On 10/01/2015 02:50 AM, Aurelien Jarno wrote: On 2015-09-30 15:09, Richard Henderson wrote: We currently pre-compute an worst case code size for any TB, which works out to be 122kB. Since the average TB size is near 1kB, this wastes quite a lot of storage. The code generation buffer is

Re: [Qemu-devel] [PATCH v4 25/26] tcg: Check for overflow via highwater mark

2015-10-01 Thread Aurelien Jarno
On 2015-09-30 15:09, Richard Henderson wrote: > We currently pre-compute an worst case code size for any TB, which > works out to be 122kB. Since the average TB size is near 1kB, this > wastes quite a lot of storage. The code generation buffer is currently computed as 1/4 of the guest RAM in

[Qemu-devel] [PATCH v4 25/26] tcg: Check for overflow via highwater mark

2015-09-30 Thread Richard Henderson
We currently pre-compute an worst case code size for any TB, which works out to be 122kB. Since the average TB size is near 1kB, this wastes quite a lot of storage. Instead, check for overflow in between generating code for each opcode. The overhead of the check isn't measurable and wastage is